3-自己动手写HashMap 增加哈希算法

public class HashMap {

    //存储元素数组
    private Entry[] entry = null;

    //记录map个数
    private int size;

    //构造器
    public HashMap() {
        this.entry = new Entry[10];
    }

    //增加新元素
    public void put(Object key, Object value) {

        Entry e = new Entry(key, value);

        //增加哈希算法
        int index=key.hashCode() % 10;

        entry[index] = e;

        size++;
    }

    //获取元素
    public Object get(Object key) {
        //增加哈希算法
        int index=key.hashCode() % 10;

        Entry e = entry[index];

        return e.getValue();
    }

    @Override
    public String toString() {

        StringBuilder sb=new StringBuilder();
        sb.append("[");
        for(int i=0;i<entry.length -1;i++)
        {
            Entry e = entry[i];
            if(e != null)
            {
                sb.append(e.getValue());
            }
            else
            {
                sb.append("null");
            }

            if(i != entry.length-1)
            {
                sb.append(",");
            }
        }
        sb.append("]");

        return sb.toString();

    }
}

测试代码

public class Demo {

    /***
     * 简单的 put get方法
     * @param args
     */
    public static void main(String[] args) {

        HashMap map=new HashMap();

        map.put("刘诗华", "罗兰");

        System.out.println(map);// [null,罗兰,null,null,null,null,null,null,null,]

        Object s = map.get("刘诗华");

        System.out.println(s);  //罗兰

    }
}