public class Entry {

    // 鍵
    private Object key;
    // 值
    private Object value;

    //構造器
    public Entry(Object key, Object value) {
        super();
        this.key = key;
        this.value = value;
    }

    public Object getKey() {
        return key;
    }

    public void setKey(Object key) {
        
 
this.key = key;
    }

    public Object getValue() {
        return value;
    }

    public void setValue(Object value) {
        this.value = value;
    }
}

public class HashMap {
    
    //存儲元素數組
    private Entry[] entry = null;
    
    //記錄map個數
    private int size;
    
    //構造器
    public HashMap() {
        
 
this.entry = new Entry[100];
    }
    
    //增加新元素
    public void put(Object key, Object value) {
        Entry e = new Entry(key, value);
        entry[size] = e;
        size++;
    }

    //獲取元素
    public Object get(Object key) {
        for (int i = 0; i < size; i++) {
            Entry e = entry[i];
            Object k 
 
= e.getKey();

            if (key.equals(k)) {
                return e.getValue();
            }
        }
        return null;
    }
}

代碼測試

public class Demo {

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

        HashMap map=new HashMap();
        
        map.put("劉詩華", "羅蘭");
        
        Object s = map.get("劉詩華");
        
        System.out.println(s);
    }
}

2-自己動寫HashMap