HashMap的自定义实现

package com.cy.collection;

/**
 * 自定义实现Map
 */
public class Map {
    private Entry[] arr = new Entry[1000];    //这里暂时不考虑扩容
    private int size;                        //这里都是private的，不暴露size属性
    
    /**
     * 1.键不能重复,如果含有这个键，就替换value
     * @param key
     * @param value
     */
    public void put(Object key, Object value){
        for(int i=0; i<size; i++){
            if(arr[i].key.equals(key)){
                arr[i].value = value;
                return;
            }
        }
        arr[size++] = new Entry(key, value);
    }
    
    //根据key获取
    public Object get(Object key){
        for(int i=0; i<size; i++){
            if(arr[i].key.equals(key)){
                return arr[i].value;
            }
        }
        return null;
    }
    
    //根据key删除
    public boolean remove(Object key){
        boolean success = false;
        for(int i=0;i<size;i++){
            if(arr[i].key.equals(key)){
                success = true;
                remove(i);
            }
        }
        return success;
    }
    private void remove(int i){
        int numMoved = size - i - 1;
        if(numMoved>0){
            System.arraycopy(arr, i+1, arr, i, numMoved);
        }
        arr[--size] = null;        //Let gc do its work
    }
    
    //containsKey
    public boolean containsKey(Object key){
        for(int i=0; i<size; i++){
            if(arr[i].key.equals(key)){
                return true;
            }
        }
        return false;
    }
    
    //containsValue 同containsKey
    
    //size
    public int size(){
        return size;
    }
}

/**
 * 用来存放键值对的条目
 */
class Entry{
    Object key;
    Object value;
    
    public Entry(Object key, Object value) {
        super();
        this.key = key;
        this.value = value;
    }
}