HashMap.java

public class HashMapCustom {
    private static final int default_capacity = 7;
    private int capacity;
    private int size;
    private Entry[] table;

    private static class Entry {
        String key;
        int value;
        Entry(String key, int value) {
            this.key = key;
            this.value = value;
        }
    }

    public HashMapCustom(int capacity) {
        this.capacity = capacity;
        table = new Entry[capacity];
        size = 0;
    }

    public HashMapCustom() {
        this(default_capacity);
    }

    private int hash(String key) {
        return Math.abs(key.hashCode()) % capacity;
    }

    public boolean put(String key, int value) {
        if (size == capacity) {
            return false;
        }
        int index = hash(key);
        while (table[index] != null && !table[index].key.equals(key)) {
            index = (index + 1) % capacity;
        }
        if (table[index] == null) {
            size++;
        }
        table[index] = new Entry(key, value);
        return true;
    }

    public int get(String key) {
        int index = hash(key);
        int start = index;
        while (table[index] != null) {
            if (table[index].key.equals(key)) {
                return table[index].value;
            }
            index = (index + 1) % capacity;
            if (index == start) {
                break;
            }
        }
        return 0;
    }

    public boolean containsKey(String key) {
        int index = hash(key);
        int start = index;
        while (table[index] != null) {
            if (table[index].key.equals(key)) {
                return true;
            }
            index = (index + 1) % capacity;
            if (index == start) {
                break;
            }
        }
        return false;
    }

    public boolean remove(String key) {
        int index = hash(key);
        int start = index;
        while (table[index] != null) {
            if (table[index].key.equals(key)) {
                table[index] = null;
                size--;
                return true;
            }
            index = (index + 1) % capacity;
            if (index == start) {
                break;
            }
        }
        return false;
    }

    public void clear() {
        table = new Entry[capacity];
        size = 0;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public boolean isFull() {
        return size == capacity;
    }
}