Android Java 数据结构示例

// Android Java Array Operations Examples
// Using Lists, Arrays, and ArrayList

import java.util.*;

// 1. Basic Array Operations
class BasicArrayOperations {

    // Create and initialize arrays
    public void createArrays() {
        // Using ArrayList (mutable)
        List<Integer> arrayList = new ArrayList<>();
        arrayList.add(1);
        arrayList.add(2);
        arrayList.add(3);
        arrayList.add(4);
        arrayList.add(5);
        System.out.println("ArrayList: " + arrayList);

        // Using Arrays (fixed size)
        int[] array = {1, 2, 3, 4, 5};
        System.out.println("Array: " + Arrays.toString(array));

        // Using LinkedList
        List<Integer> linkedList = new LinkedList<>();
        linkedList.add(1);
        linkedList.add(2);
        linkedList.add(3);
        linkedList.add(4);
        linkedList.add(5);
        System.out.println("LinkedList: " + linkedList);

        // Create from existing collection
        List<Integer> listFromArray = new ArrayList<>();
        for (int num : array) {
            listFromArray.add(num);
        }
        System.out.println("List from array: " + listFromArray);
    }

    // Access elements
    public void accessElements(List<Integer> list) {
        System.out.println("First element: " + list.get(0));
        System.out.println("Last element: " + list.get(list.size() - 1));
        System.out.println("Element at index 2: " + list.get(2));

        // Safe access
        if (list.size() > 10) {
            System.out.println("Element at index 10: " + list.get(10));
        } else {
            System.out.println("Element at index 10: Index out of bounds");
        }
    }

    // Check element existence
    public void checkElement(List<Integer> list, int element) {
        System.out.println("Contains " + element + ": " + list.contains(element));
        System.out.println("Index of " + element + ": " + list.indexOf(element));
        System.out.println("Last index of " + element + ": " + list.lastIndexOf(element));
    }

    // Get array size
    public void getSize(List<Integer> list) {
        System.out.println("Size: " + list.size());
        System.out.println("Is empty: " + list.isEmpty());
    }
}

// 2. Mutable Array Operations
class MutableArrayOperations {

    // Add elements
    public void addElements() {
        List<Integer> list = new ArrayList<>();

        // Add single element
        list.add(1);
        list.add(2);
        System.out.println("After adding: " + list);

        // Add at specific index
        list.add(1, 10);
        System.out.println("After insert at index 1: " + list);

        // Add all from another collection
        List<Integer> moreNumbers = new ArrayList<>();
        moreNumbers.add(20);
        moreNumbers.add(30);
        moreNumbers.add(40);
        list.addAll(moreNumbers);
        System.out.println("After addAll: " + list);

        // Add at index from another collection
        List<Integer> atStart = new ArrayList<>();
        atStart.add(100);
        atStart.add(200);
        list.addAll(2, atStart);
        System.out.println("After addAll at index: " + list);
    }

    // Remove elements
    public void removeElements() {
        List<Integer> list = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 3, 6));

        // Remove by value (first occurrence)
        list.remove(Integer.valueOf(3));
        System.out.println("After remove(3): " + list);

        // Remove by index
        list.remove(2);
        System.out.println("After removeAt(2): " + list);

        // Remove first occurrence
        list.remove(Integer.valueOf(3));
        System.out.println("After remove first 3: " + list);

        // Remove all matching
        List<Integer> numbers = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5));
        numbers.removeAll(Arrays.asList(2, 4));
        System.out.println("After removeAll(2,4): " + numbers);

        // Remove range using subList
        List<Integer> rangeList = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7));
        rangeList.subList(2, 5).clear();
        System.out.println("After remove range 2-5: " + rangeList);

        // Clear all
        rangeList.clear();
        System.out.println("After clear: " + rangeList);
    }

    // Update elements
    public void updateElements() {
        List<Integer> list = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5));

        // Update by index
        list.set(2, 30);
        System.out.println("After update index 2: " + list);

        // Update in place
        for (int i = 0; i < list.size(); i++) {
            list.set(i, list.get(i) * 10);
        }
        System.out.println("After in-place update: " + list);

        // Replace all
        List<Integer> newList = new ArrayList<>();
        for (int num : list) {
            newList.add(num * 2);
        }
        System.out.println("After map * 2: " + newList);
    }
}

// 3. Array Searching
class ArraySearching {

    // Linear search
    public int linearSearch(List<Integer> list, int target) {
        for (int i = 0; i < list.size(); i++) {
            if (list.get(i) == target) {
                return i;
            }
        }
        return -1;
    }

    // Binary search (requires sorted list)
    public int binarySearch(List<Integer> list, int target) {
        int left = 0;
        int right = list.size() - 1;

        while (left <= right) {
            int mid = left + (right - left) / 2;

            if (list.get(mid) == target) {
                return mid;
            } else if (list.get(mid) < target) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }

        return -1;
    }

    // Find max and min
    public int[] findMaxMin(List<Integer> list) {
        if (list.isEmpty()) return null;

        int max = list.get(0);
        int min = list.get(0);

        for (int element : list) {
            if (element > max) max = element;
            if (element < min) min = element;
        }

        return new int[]{max, min};
    }

    // Find duplicates
    public List<Integer> findDuplicates(List<Integer> list) {
        Set<Integer> seen = new HashSet<>();
        Set<Integer> duplicates = new HashSet<>();

        for (int element : list) {
            if (!seen.add(element)) {
                duplicates.add(element);
            }
        }

        return new ArrayList<>(duplicates);
    }

    // Count occurrences
    public int countOccurrences(List<Integer> list, int target) {
        int count = 0;
        for (int element : list) {
            if (element == target) {
                count++;
            }
        }
        return count;
    }
}

// 4. Array Sorting
class ArraySorting {

    // Built-in sort ascending
    public void sortAscending(List<Integer> list) {
        Collections.sort(list);
    }

    // Built-in sort descending
    public void sortDescending(List<Integer> list) {
        Collections.sort(list, Collections.reverseOrder());
    }

    // Sort by custom comparator
    public void sortCustom(List<String> list) {
        // Sort by length
        Collections.sort(list, new Comparator<String>() {
            @Override
            public int compare(String s1, String s2) {
                return Integer.compare(s1.length(), s2.length());
            }
        });
    }

    // Bubble sort (manual implementation)
    public void bubbleSort(List<Integer> arr) {
        int n = arr.size();
        for (int i = 0; i < n - 1; i++) {
            for (int j = 0; j < n - i - 1; j++) {
                if (arr.get(j) > arr.get(j + 1)) {
                    // Swap
                    int temp = arr.get(j);
                    arr.set(j, arr.get(j + 1));
                    arr.set(j + 1, temp);
                }
            }
        }
    }

    // Selection sort
    public void selectionSort(List<Integer> arr) {
        int n = arr.size();
        for (int i = 0; i < n - 1; i++) {
            int minIdx = i;
            for (int j = i + 1; j < n; j++) {
                if (arr.get(j) < arr.get(minIdx)) {
                    minIdx = j;
                }
            }
            // Swap
            int temp = arr.get(minIdx);
            arr.set(minIdx, arr.get(i));
            arr.set(i, temp);
        }
    }

    // Quick sort
    public void quickSort(List<Integer> arr, int low, int high) {
        if (low < high) {
            int pivotIndex = partition(arr, low, high);
            quickSort(arr, low, pivotIndex - 1);
            quickSort(arr, pivotIndex + 1, high);
        }
    }

    private int partition(List<Integer> arr, int low, int high) {
        int pivot = arr.get(high);
        int i = low - 1;

        for (int j = low; j < high; j++) {
            if (arr.get(j) <= pivot) {
                i++;
                // Swap arr[i] and arr[j]
                int temp = arr.get(i);
                arr.set(i, arr.get(j));
                arr.set(j, temp);
            }
        }

        // Swap arr[i+1] and arr[high]
        int temp = arr.get(i + 1);
        arr.set(i + 1, arr.get(high));
        arr.set(high, temp);

        return i + 1;
    }
}

// 5. Array Filtering and Mapping
class ArrayTransformations {

    // Filter elements
    public List<Integer> filterEven(List<Integer> list) {
        List<Integer> result = new ArrayList<>();
        for (int num : list) {
            if (num % 2 == 0) {
                result.add(num);
            }
        }
        return result;
    }

    public List<Integer> filterGreaterThan(List<Integer> list, int threshold) {
        List<Integer> result = new ArrayList<>();
        for (int num : list) {
            if (num > threshold) {
                result.add(num);
            }
        }
        return result;
    }

    // Map elements
    public List<Integer> doubleElements(List<Integer> list) {
        List<Integer> result = new ArrayList<>();
        for (int num : list) {
            result.add(num * 2);
        }
        return result;
    }

    public List<String> toStringList(List<Integer> list) {
        List<String> result = new ArrayList<>();
        for (int num : list) {
            result.add("Number: " + num);
        }
        return result;
    }

    // Sum
    public int sum(List<Integer> list) {
        int total = 0;
        for (int num : list) {
            total += num;
        }
        return total;
    }

    // Product
    public int product(List<Integer> list) {
        int result = 1;
        for (int num : list) {
            result *= num;
        }
        return result;
    }

    // Join to string
    public String joinToString(List<Integer> list, String delimiter) {
        StringBuilder sb = new StringBuilder();
        sb.append("[");
        for (int i = 0; i < list.size(); i++) {
            if (i > 0) sb.append(delimiter);
            sb.append(list.get(i));
        }
        sb.append("]");
        return sb.toString();
    }

    // Partition
    public Map<String, List<Integer>> partitionEvenOdd(List<Integer> list) {
        Map<String, List<Integer>> result = new HashMap<>();
        List<Integer> even = new ArrayList<>();
        List<Integer> odd = new ArrayList<>();

        for (int num : list) {
            if (num % 2 == 0) {
                even.add(num);
            } else {
                odd.add(num);
            }
        }

        result.put("even", even);
        result.put("odd", odd);
        return result;
    }

    // Group by length
    public Map<Integer, List<String>> groupByLength(List<String> list) {
        Map<Integer, List<String>> result = new HashMap<>();
        for (String s : list) {
            int len = s.length();
            if (!result.containsKey(len)) {
                result.put(len, new ArrayList<>());
            }
            result.get(len).add(s);
        }
        return result;
    }

    // Chunk
    public List<List<Integer>> chunkList(List<Integer> list, int size) {
        List<List<Integer>> chunks = new ArrayList<>();
        for (int i = 0; i < list.size(); i += size) {
            int end = Math.min(i + size, list.size());
            chunks.add(new ArrayList<>(list.subList(i, end)));
        }
        return chunks;
    }
}

// Main demonstration
class ArrayOperationsDemo {
    public static void demonstrateArrayOperations() {
        System.out.println("=== Android Java Array Operations Examples ===\n");

        // 1. Basic operations
        System.out.println("--- 1. Basic Array Operations ---");
        BasicArrayOperations basicOps = new BasicArrayOperations();
        basicOps.createArrays();

        List<Integer> sampleList = new ArrayList<>(Arrays.asList(10, 20, 30, 40, 50));
        basicOps.accessElements(sampleList);
        basicOps.checkElement(sampleList, 30);
        basicOps.getSize(sampleList);

        // 2. Mutable operations
        System.out.println("\n--- 2. Mutable Array Operations ---");
        MutableArrayOperations mutableOps = new MutableArrayOperations();
        mutableOps.addElements();
        mutableOps.removeElements();
        mutableOps.updateElements();

        // 3. Searching
        System.out.println("\n--- 3. Array Searching ---");
        ArraySearching searching = new ArraySearching();
        List<Integer> searchList = new ArrayList<>(Arrays.asList(1, 5, 3, 9, 2, 8, 7));
        System.out.println("Linear search for 9: " + searching.linearSearch(searchList, 9));

        List<Integer> sortedList = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9));
        System.out.println("Binary search for 5: " + searching.binarySearch(sortedList, 5));

        int[] maxMin = searching.findMaxMin(searchList);
        System.out.println("Max/Min: " + maxMin[0] + "/" + maxMin[1]);
        System.out.println("Duplicates: " + searching.findDuplicates(Arrays.asList(1, 2, 2, 3, 3, 3)));
        System.out.println("Count of 3: " + searching.countOccurrences(Arrays.asList(1, 3, 3, 2, 3), 3));

        // 4. Sorting
        System.out.println("\n--- 4. Array Sorting ---");
        ArraySorting sorting = new ArraySorting();
        List<Integer> unsorted = new ArrayList<>(Arrays.asList(5, 2, 8, 1, 9, 3));
        System.out.println("Original: " + unsorted);
        sorting.sortAscending(unsorted);
        System.out.println("Sorted ascending: " + unsorted);

        List<Integer> sortDescending = new ArrayList<>(Arrays.asList(5, 2, 8, 1, 9, 3));
        sorting.sortDescending(sortDescending);
        System.out.println("Sorted descending: " + sortDescending);

        // 5. Transformations
        System.out.println("\n--- 5. Array Transformations ---");
        ArrayTransformations transformations = new ArrayTransformations();
        List<Integer> numbers = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
        System.out.println("Filter even: " + transformations.filterEven(numbers));
        System.out.println("Filter > 5: " + transformations.filterGreaterThan(numbers, 5));
        System.out.println("Double elements: " + transformations.doubleElements(numbers));
        System.out.println("Sum: " + transformations.sum(numbers));
        System.out.println("Partition even/odd: " + transformations.partitionEvenOdd(numbers));
        System.out.println("Chunk by 3: " + transformations.chunkList(numbers, 3));

        System.out.println("\n=== All Array Operations Examples Completed ===");
    }
}

// Android Java Hash Table Operations Examples
// Using HashMap, HashSet, and LinkedHashMap

import java.util.*;
import java.util.stream.Collectors;

// 1. HashMap Basic Operations
class HashMapOperations {

    // Create and initialize HashMap
    public void createHashMap() {
        // Using HashMap
        Map<String, Integer> hashMap = new HashMap<>();
        hashMap.put("Apple", 10);
        hashMap.put("Banana", 20);
        hashMap.put("Orange", 30);
        hashMap.put("Grape", 40);
        System.out.println("HashMap: " + hashMap);

        // Using LinkedHashMap (preserves insertion order)
        Map<String, Integer> linkedHashMap = new LinkedHashMap<>();
        linkedHashMap.put("Apple", 10);
        linkedHashMap.put("Banana", 20);
        linkedHashMap.put("Orange", 30);
        System.out.println("LinkedHashMap: " + linkedHashMap);

        // Using TreeMap (sorted by keys)
        Map<String, Integer> treeMap = new TreeMap<>();
        treeMap.put("Apple", 10);
        treeMap.put("Banana", 20);
        treeMap.put("Orange", 30);
        System.out.println("TreeMap: " + treeMap);

        // Initialize from another map
        Map<String, Integer> copyMap = new HashMap<>(hashMap);
        System.out.println("Copied map: " + copyMap);
    }

    // Access elements
    public void accessElements(Map<String, Integer> map) {
        System.out.println("Value for 'Apple': " + map.get("Apple"));
        System.out.println("Value for 'Pear' (default): " + map.getOrDefault("Pear", 0));

        // Check if key exists
        System.out.println("Contains key 'Apple': " + map.containsKey("Apple"));
        System.out.println("Contains value 20: " + map.containsValue(20));
    }

    // Modify elements
    public void modifyElements(Map<String, Integer> map) {
        System.out.println("Before: " + map);

        // Update existing key
        map.put("Apple", 15);

        // Put if absent
        map.putIfAbsent("Pear", 25);

        // Replace if exists
        map.replace("Banana", 22);

        // Replace with old value check
        map.replace("Orange", 30, 35);

        // Compute if absent
        map.computeIfAbsent("Mango", k -> 50);

        // Compute if present
        map.computeIfPresent("Grape", (k, v) -> v + 5);

        // Merge
        map.merge("Apple", 10, Integer::sum);

        System.out.println("After: " + map);
    }

    // Remove elements
    public void removeElements(Map<String, Integer> map) {
        System.out.println("Before: " + map);

        // Remove by key
        map.remove("Apple");

        // Remove by key and value
        map.remove("Banana", 20);

        // Clear all
        map.clear();

        System.out.println("After: " + map);
    }

    // Iterate over map
    public void iterateMap(Map<String, Integer> map) {
        System.out.println("Iterate keys:");
        for (String key : map.keySet()) {
            System.out.println("  Key: " + key);
        }

        System.out.println("Iterate values:");
        for (Integer value : map.values()) {
            System.out.println("  Value: " + value);
        }

        System.out.println("Iterate entries:");
        for (Map.Entry<String, Integer> entry : map.entrySet()) {
            System.out.println("  " + entry.getKey() + " = " + entry.getValue());
        }

        // Using forEach (Java 8+)
        System.out.println("Using forEach:");
        map.forEach((k, v) -> System.out.println("  " + k + " -> " + v));
    }

    // Get size
    public void getSize(Map<String, Integer> map) {
        System.out.println("Size: " + map.size());
        System.out.println("Is empty: " + map.isEmpty());
    }
}

// 2. HashSet Operations
class HashSetOperations {

    // Create and initialize HashSet
    public void createHashSet() {
        // Using HashSet
        Set<Integer> hashSet = new HashSet<>();
        hashSet.add(1);
        hashSet.add(2);
        hashSet.add(3);
        hashSet.add(4);
        hashSet.add(5);
        System.out.println("HashSet: " + hashSet);

        // Using LinkedHashSet (preserves insertion order)
        Set<Integer> linkedHashSet = new LinkedHashSet<>();
        linkedHashSet.add(1);
        linkedHashSet.add(2);
        linkedHashSet.add(3);
        System.out.println("LinkedHashSet: " + linkedHashSet);

        // Using TreeSet (sorted)
        Set<Integer> treeSet = new TreeSet<>();
        treeSet.add(5);
        treeSet.add(2);
        treeSet.add(8);
        treeSet.add(1);
        System.out.println("TreeSet: " + treeSet);

        // Initialize from collection
        Set<Integer> fromList = new HashSet<>(Arrays.asList(1, 2, 3, 4, 5));
        System.out.println("From list: " + fromList);
    }

    // Basic operations
    public void basicOperations(Set<Integer> set) {
        System.out.println("Original: " + set);

        // Add elements
        set.add(6);
        set.addAll(Arrays.asList(7, 8, 9));
        System.out.println("After adding: " + set);

        // Check existence
        System.out.println("Contains 5: " + set.contains(5));
        System.out.println("Contains 10: " + set.contains(10));

        // Remove elements
        set.remove(5);
        set.removeAll(Arrays.asList(2, 4));
        System.out.println("After removal: " + set);
    }

    // Set operations
    public void setOperations() {
        Set<Integer> set1 = new HashSet<>(Arrays.asList(1, 2, 3, 4, 5));
        Set<Integer> set2 = new HashSet<>(Arrays.asList(4, 5, 6, 7, 8));

        // Union
        Set<Integer> union = new HashSet<>(set1);
        union.addAll(set2);
        System.out.println("Union: " + union);

        // Intersection
        Set<Integer> intersection = new HashSet<>(set1);
        intersection.retainAll(set2);
        System.out.println("Intersection: " + intersection);

        // Difference
        Set<Integer> difference = new HashSet<>(set1);
        difference.removeAll(set2);
        System.out.println("Difference (set1 - set2): " + difference);

        // Check subset
        Set<Integer> subset = new HashSet<>(Arrays.asList(1, 2));
        System.out.println("Is subset: " + set1.containsAll(subset));
    }

    // Iterate
    public void iterateSet(Set<Integer> set) {
        System.out.println("Iterate using for-each:");
        for (Integer item : set) {
            System.out.println("  " + item);
        }

        System.out.println("Using forEach:");
        set.forEach(item -> System.out.println("  " + item));

        System.out.println("Using iterator:");
        Iterator<Integer> iterator = set.iterator();
        while (iterator.hasNext()) {
            System.out.println("  " + iterator.next());
        }
    }
}

// 3. Advanced Map Operations
class AdvancedMapOperations {

    // Sort map by values
    public Map<String, Integer> sortByValue(Map<String, Integer> map) {
        List<Map.Entry<String, Integer>> list = new ArrayList<>(map.entrySet());
        list.sort(new Comparator<Map.Entry<String, Integer>>() {
            @Override
            public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {
                return o1.getValue().compareTo(o2.getValue());
            }
        });

        Map<String, Integer> result = new LinkedHashMap<>();
        for (Map.Entry<String, Integer> entry : list) {
            result.put(entry.getKey(), entry.getValue());
        }
        return result;
    }

    // Filter map by keys
    public Map<String, Integer> filterByKeys(Map<String, Integer> map, Set<String> keys) {
        Map<String, Integer> result = new HashMap<>();
        for (String key : keys) {
            if (map.containsKey(key)) {
                result.put(key, map.get(key));
            }
        }
        return result;
    }

    // Filter map by values
    public Map<String, Integer> filterByValues(Map<String, Integer> map, int threshold) {
        Map<String, Integer> result = new HashMap<>();
        for (Map.Entry<String, Integer> entry : map.entrySet()) {
            if (entry.getValue() > threshold) {
                result.put(entry.getKey(), entry.getValue());
            }
        }
        return result;
    }

    // Invert map (swap keys and values)
    public <K, V> Map<V, K> invertMap(Map<K, V> map) {
        Map<V, K> inverted = new HashMap<>();
        for (Map.Entry<K, V> entry : map.entrySet()) {
            inverted.put(entry.getValue(), entry.getKey());
        }
        return inverted;
    }

    // Group list items by key
    public <T> Map<String, List<T>> groupBy(List<T> items, java.util.function.Function<T, String> keyExtractor) {
        Map<String, List<T>> result = new HashMap<>();
        for (T item : items) {
            String key = keyExtractor.apply(item);
            if (!result.containsKey(key)) {
                result.put(key, new ArrayList<>());
            }
            result.get(key).add(item);
        }
        return result;
    }

    // Map transformations
    public <K, V1, V2> Map<K, V2> mapValues(Map<K, V1> map, java.util.function.Function<V1, V2> mapper) {
        Map<K, V2> result = new HashMap<>();
        for (Map.Entry<K, V1> entry : map.entrySet()) {
            result.put(entry.getKey(), mapper.apply(entry.getValue()));
        }
        return result;
    }
}

// 4. Cache Implementation
class SimpleCache<K, V> {
    private Map<K, V> cache;
    private int maxSize;

    public SimpleCache(int maxSize) {
        this.maxSize = maxSize;
        this.cache = new LinkedHashMap<K, V>(maxSize, 0.75f, true) {
            @Override
            protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
                return size() > SimpleCache.this.maxSize;
            }
        };
    }

    public void put(K key, V value) {
        cache.put(key, value);
    }

    public V get(K key) {
        return cache.get(key);
    }

    public boolean containsKey(K key) {
        return cache.containsKey(key);
    }

    public void remove(K key) {
        cache.remove(key);
    }

    public void clear() {
        cache.clear();
    }

    public int size() {
        return cache.size();
    }

    public Set<K> keySet() {
        return cache.keySet();
    }
}

// 5. Multi-map (one key, multiple values)
class Multimap<K, V> {
    private Map<K, List<V>> map = new HashMap<>();

    public void put(K key, V value) {
        if (!map.containsKey(key)) {
            map.put(key, new ArrayList<>());
        }
        map.get(key).add(value);
    }

    public List<V> get(K key) {
        return map.getOrDefault(key, new ArrayList<>());
    }

    public Set<K> keySet() {
        return map.keySet();
    }

    public boolean containsKey(K key) {
        return map.containsKey(key);
    }

    public int size() {
        return map.size();
    }

    public void remove(K key) {
        map.remove(key);
    }

    public void clear() {
        map.clear();
    }
}

// Main demonstration
class HashTableDemo {
    public static void demonstrateHashTableOperations() {
        System.out.println("=== Android Java Hash Table Operations Examples ===\n");

        // 1. HashMap operations
        System.out.println("--- 1. HashMap Operations ---");
        HashMapOperations hashMapOps = new HashMapOperations();
        hashMapOps.createHashMap();

        Map<String, Integer> sampleMap = new HashMap<>();
        sampleMap.put("Apple", 10);
        sampleMap.put("Banana", 20);
        sampleMap.put("Orange", 30);
        sampleMap.put("Grape", 40);

        hashMapOps.accessElements(sampleMap);
        hashMapOps.modifyElements(sampleMap);
        hashMapOps.iterateMap(sampleMap);
        hashMapOps.getSize(sampleMap);

        // 2. HashSet operations
        System.out.println("\n--- 2. HashSet Operations ---");
        HashSetOperations hashSetOps = new HashSetOperations();
        hashSetOps.createHashSet();
        hashSetOps.setOperations();

        Set<Integer> sampleSet = new HashSet<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9));
        hashSetOps.iterateSet(sampleSet);

        // 3. Advanced map operations
        System.out.println("\n--- 3. Advanced Map Operations ---");
        AdvancedMapOperations advancedOps = new AdvancedMapOperations();

        Map<String, Integer> unsortedMap = new HashMap<>();
        unsortedMap.put("Apple", 40);
        unsortedMap.put("Banana", 10);
        unsortedMap.put("Orange", 30);
        unsortedMap.put("Grape", 20);

        Map<String, Integer> sortedByValue = advancedOps.sortByValue(unsortedMap);
        System.out.println("Sorted by value: " + sortedByValue);

        Map<String, Integer> filtered = advancedOps.filterByValues(unsortedMap, 15);
        System.out.println("Filtered (> 15): " + filtered);

        // 4. Cache example
        System.out.println("\n--- 4. Simple Cache ---");
        SimpleCache<String, String> cache = new SimpleCache<>(3);
        cache.put("key1", "value1");
        cache.put("key2", "value2");
        cache.put("key3", "value3");
        System.out.println("Cache size: " + cache.size());
        System.out.println("Get key1: " + cache.get("key1"));

        cache.put("key4", "value4"); // This should evict key1 (LRU)
        System.out.println("After adding key4, size: " + cache.size());
        System.out.println("Contains key1: " + cache.containsKey("key1"));

        // 5. Multimap example
        System.out.println("\n--- 5. Multimap ---");
        Multimap<String, Integer> multimap = new Multimap<>();
        multimap.put("fruits", 1);
        multimap.put("fruits", 2);
        multimap.put("fruits", 3);
        multimap.put("vegetables", 10);
        multimap.put("vegetables", 20);

        System.out.println("Fruits: " + multimap.get("fruits"));
        System.out.println("Vegetables: " + multimap.get("vegetables"));

        System.out.println("\n=== All Hash Table Operations Examples Completed ===");
    }
}

// Android Java Linked List Operations Examples
// Using LinkedList and custom implementations

import java.util.*;

// 1. Java LinkedList Operations
class JavaLinkedListOperations {

    public void demonstrateLinkedList() {
        // Create LinkedList
        LinkedList<String> list = new LinkedList<>();

        // Add elements
        list.add("Apple");
        list.add("Banana");
        list.addFirst("First");
        list.addLast("Last");
        list.add(2, "Middle");
        System.out.println("After adding: " + list);

        // Access elements
        System.out.println("First: " + list.getFirst());
        System.out.println("Last: " + list.getLast());
        System.out.println("Element at index 2: " + list.get(2));

        // Remove elements
        list.removeFirst();
        list.removeLast();
        list.remove("Middle");
        System.out.println("After removal: " + list);

        // Using as stack
        LinkedList<Integer> stack = new LinkedList<>();
        stack.push(1);
        stack.push(2);
        stack.push(3);
        System.out.println("Stack: " + stack);
        System.out.println("Pop: " + stack.pop());
        System.out.println("Peek: " + stack.peek());

        // Using as queue
        LinkedList<Integer> queue = new LinkedList<>();
        queue.offer(1);
        queue.offer(2);
        queue.offer(3);
        System.out.println("Queue: " + queue);
        System.out.println("Poll: " + queue.poll());
        System.out.println("Peek: " + queue.peek());
    }
}

// 2. Singly Linked List Implementation
class SinglyLinkedList<T> {
    private Node<T> head;
    private int size;

    private static class Node<T> {
        T data;
        Node<T> next;

        Node(T data) {
            this.data = data;
            this.next = null;
        }
    }

    // Add at end
    public void add(T data) {
        Node<T> newNode = new Node<>(data);
        if (head == null) {
            head = newNode;
        } else {
            Node<T> current = head;
            while (current.next != null) {
                current = current.next;
            }
            current.next = newNode;
        }
        size++;
    }

    // Add at beginning
    public void addFirst(T data) {
        Node<T> newNode = new Node<>(data);
        newNode.next = head;
        head = newNode;
        size++;
    }

    // Add at index
    public void add(int index, T data) {
        if (index < 0 || index > size) {
            throw new IndexOutOfBoundsException();
        }

        if (index == 0) {
            addFirst(data);
        } else if (index == size) {
            add(data);
        } else {
            Node<T> newNode = new Node<>(data);
            Node<T> current = head;
            for (int i = 0; i < index - 1; i++) {
                current = current.next;
            }
            newNode.next = current.next;
            current.next = newNode;
            size++;
        }
    }

    // Remove first
    public T removeFirst() {
        if (head == null) {
            throw new NoSuchElementException();
        }
        T data = head.data;
        head = head.next;
        size--;
        return data;
    }

    // Remove last
    public T removeLast() {
        if (head == null) {
            throw new NoSuchElementException();
        }
        if (head.next == null) {
            T data = head.data;
            head = null;
            size--;
            return data;
        }
        Node<T> current = head;
        while (current.next.next != null) {
            current = current.next;
        }
        T data = current.next.data;
        current.next = null;
        size--;
        return data;
    }

    // Remove at index
    public T remove(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException();
        }
        if (index == 0) {
            return removeFirst();
        }
        Node<T> current = head;
        for (int i = 0; i <index - 1; i++) {
            current = current.next;
        }
        T data = current.next.data;
        current.next = current.next.next;
        size--;
        return data;
    }

    // Get first
    public T getFirst() {
        if (head == null) {
            throw new NoSuchElementException();
        }
        return head.data;
    }

    // Get last
    public T getLast() {
        if (head == null) {
            throw new NoSuchElementException();
        }
        Node<T> current = head;
        while (current.next != null) {
            current = current.next;
        }
        return current.data;
    }

    // Get at index
    public T get(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException();
        }
        Node<T> current = head;
        for (int i = 0; i < index; i++) {
            current = current.next;
        }
        return current.data;
    }

    // Size
    public int size() {
        return size;
    }

    // Is empty
    public boolean isEmpty() {
        return head == null;
    }

    // Clear
    public void clear() {
        head = null;
        size = 0;
    }

    // To array
    public Object[] toArray() {
        Object[] array = new Object[size];
        Node<T> current = head;
        for (int i = 0; i < size; i++) {
            array[i] = current.data;
            current = current.next;
        }
        return array;
    }

    // Reverse
    public void reverse() {
        Node<T> prev = null;
        Node<T> current = head;
        Node<T> next = null;

        while (current != null) {
            next = current.next;
            current.next = prev;
            prev = current;
            current = next;
        }
        head = prev;
    }

    // Contains
    public boolean contains(T data) {
        Node<T> current = head;
        while (current != null) {
            if (Objects.equals(current.data, data)) {
                return true;
            }
            current = current.next;
        }
        return false;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder("[");
        Node<T> current = head;
        while (current != null) {
            sb.append(current.data);
            if (current.next != null) {
                sb.append(" -> ");
            }
            current = current.next;
        }
        sb.append("]");
        return sb.toString();
    }
}

// 3. Doubly Linked List Implementation
class DoublyLinkedList<T> {
    private Node<T> head;
    private Node<T> tail;
    private int size;

    private static class Node<T> {
        T data;
        Node<T> prev;
        Node<T> next;

        Node(T data) {
            this.data = data;
            this.prev = null;
            this.next = null;
        }
    }

    // Add at end
    public void add(T data) {
        Node<T> newNode = new Node<>(data);
        if (tail == null) {
            head = tail = newNode;
        } else {
            tail.next = newNode;
            newNode.prev = tail;
            tail = newNode;
        }
        size++;
    }

    // Add at beginning
    public void addFirst(T data) {
        Node<T> newNode = new Node<>(data);
        if (head == null) {
            head = tail = newNode;
        } else {
            newNode.next = head;
            head.prev = newNode;
            head = newNode;
        }
        size++;
    }

    // Remove first
    public T removeFirst() {
        if (head == null) {
            throw new NoSuchElementException();
        }
        T data = head.data;
        head = head.next;
        if (head != null) {
            head.prev = null;
        } else {
            tail = null;
        }
        size--;
        return data;
    }

    // Remove last
    public T removeLast() {
        if (tail == null) {
            throw new NoSuchElementException();
        }
        T data = tail.data;
        tail = tail.prev;
        if (tail != null) {
            tail.next = null;
        } else {
            head = null;
        }
        size--;
        return data;
    }

    // Get first
    public T getFirst() {
        if (head == null) {
            throw new NoSuchElementException();
        }
        return head.data;
    }

    // Get last
    public T getLast() {
        if (tail == null) {
            throw new NoSuchElementException();
        }
        return tail.data;
    }

    // Size
    public int size() {
        return size;
    }

    // Is empty
    public boolean isEmpty() {
        return head == null;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder("[");
        Node<T> current = head;
        while (current != null) {
            sb.append(current.data);
            if (current.next != null) {
                sb.append(" <-> ");
            }
            current = current.next;
        }
        sb.append("]");
        return sb.toString();
    }

    // Iterate forward
    public void iterateForward() {
        System.out.print("Forward: ");
        Node<T> current = head;
        while (current != null) {
            System.out.print(current.data + " ");
            current = current.next;
        }
        System.out.println();
    }

    // Iterate backward
    public void iterateBackward() {
        System.out.print("Backward: ");
        Node<T> current = tail;
        while (current != null) {
            System.out.print(current.data + " ");
            current = current.prev;
        }
        System.out.println();
    }
}

// 4. Linked List Algorithms
class LinkedListAlgorithms {

    // Detect cycle (Floyd's cycle detection)
    public static <T> boolean hasCycle(SinglyLinkedList<T> list) {
        // This would require exposing the internal nodes
        // For demonstration, showing algorithm concept
        return false;
    }

    // Find middle element
    public static <T> T findMiddle(LinkedList<T> list) {
        if (list.isEmpty()) {
            throw new NoSuchElementException();
        }

        ListIterator<T> slow = list.listIterator();
        ListIterator<T> fast = list.listIterator();

        while (fast.hasNext() && slow.hasNext()) {
            fast.next();
            if (fast.hasNext()) {
                fast.next();
                slow.next();
            } else {
                break;
            }
        }

        return slow.next();
    }

    // Check if palindrome
    public static boolean isPalindrome(LinkedList<Character> list) {
        if (list.size() <= 1) {
            return true;
        }

        // Compare first and last, moving inward
        int left = 0;
        int right = list.size() - 1;

        while (left < right) {
            if (!list.get(left).equals(list.get(right))) {
                return false;
            }
            left++;
            right--;
        }

        return true;
    }

    // Remove duplicates from sorted list
    public static <T extends Comparable<T>> void removeDuplicates(LinkedList<T> list) {
        if (list.size() <= 1) {
            return;
        }

        Collections.sort(list);

        Iterator<T> iterator = list.iterator();
        T prev = iterator.next();

        while (iterator.hasNext()) {
            T current = iterator.next();
            if (current.compareTo(prev) == 0) {
                iterator.remove();
            } else {
                prev = current;
            }
        }
    }
}

// Main demonstration
class LinkedListDemo {
    public static void demonstrateLinkedListOperations() {
        System.out.println("=== Android Java Linked List Operations Examples ===\n");

        // 1. Java LinkedList
        System.out.println("--- 1. Java LinkedList ---");
        JavaLinkedListOperations javaListOps = new JavaLinkedListOperations();
        javaListOps.demonstrateLinkedList();

        // 2. Singly Linked List
        System.out.println("\n--- 2. Singly Linked List ---");
        SinglyLinkedList<Integer> singlyList = new SinglyLinkedList<>();
        singlyList.add(1);
        singlyList.add(2);
        singlyList.add(3);
        singlyList.addFirst(0);
        singlyList.add(2, 99);
        System.out.println("Singly linked list: " + singlyList);
        System.out.println("First: " + singlyList.getFirst());
        System.out.println("Last: " + singlyList.getLast());
        System.out.println("Get(2): " + singlyList.get(2));
        System.out.println("Contains 99: " + singlyList.contains(99));
        System.out.println("Size: " + singlyList.size());

        singlyList.reverse();
        System.out.println("After reverse: " + singlyList);

        singlyList.removeFirst();
        singlyList.removeLast();
        System.out.println("After removing first and last: " + singlyList);

        // 3. Doubly Linked List
        System.out.println("\n--- 3. Doubly Linked List ---");
        DoublyLinkedList<String> doublyList = new DoublyLinkedList<>();
        doublyList.add("A");
        doublyList.add("B");
        doublyList.add("C");
        doublyList.addFirst("Start");
        doublyList.addLast("End");
        System.out.println("Doubly linked list: " + doublyList);
        doublyList.iterateForward();
        doublyList.iterateBackward();

        System.out.println("Remove first: " + doublyList.removeFirst());
        System.out.println("Remove last: " + doublyList.removeLast());
        System.out.println("After removals: " + doublyList);

        // 4. Algorithms
        System.out.println("\n--- 4. Linked List Algorithms ---");
        LinkedList<Integer> numberList = new LinkedList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9));
        System.out.println("Find middle of " + numberList + ": " + LinkedListAlgorithms.findMiddle(numberList));

        LinkedList<Character> charList = new LinkedList<>(Arrays.asList('r', 'a', 'c', 'e', 'c', 'a', 'r'));
        System.out.println("Is palindrome " + charList + ": " + LinkedListAlgorithms.isPalindrome(charList));

        LinkedList<Character> notPalindrome = new LinkedList<>(Arrays.asList('h', 'e', 'l', 'l', 'o'));
        System.out.println("Is palindrome " + notPalindrome + ": " + LinkedListAlgorithms.isPalindrome(notPalindrome));

        LinkedList<Integer> withDuplicates = new LinkedList<>(Arrays.asList(1, 2, 2, 3, 3, 4, 5));
        System.out.println("Before removing duplicates: " + withDuplicates);
        LinkedListAlgorithms.removeDuplicates(withDuplicates);
        System.out.println("After removing duplicates: " + withDuplicates);

        System.out.println("\n=== All Linked List Operations Examples Completed ===");
    }
}