自定义实现HashMap类

package 容器;

public class Node3 {
	int hash;
	K key;
	V value;
	Node3 next;
}

package 容器;


public class 测试14自定义实现HashMap类02 {
	Node3[] table;	//位桶数组
	int size;//存储此类实际存储元素的多少
	
	public 测试14自定义实现HashMap类02() {
		table = new Node3[16];	//定义为2的整数次幂，如同ArrayList一样，需要考虑数组扩容问题
	}
	
	public void put(K key,V value) {
		Node3 newNode = new Node3();
		newNode.hash = myHash(key.hashCode(), table.length);
		newNode.key = key;
		newNode.value = value;
		newNode.next = null;
		
		Node3 temp = table[newNode.hash];
		Node3 iterLast = null;//为了保存接下来遍历后的最后一个元素
		boolean keyRepeat = false;
		
		//遗留代码，如果要完善，考虑数组扩容的问题
		
		
		if (temp == null) {
			//数组为空，直接存在第一个位置
			table[newNode.hash] = newNode;
			size ++;
		}else {
			//数组不为空，需要遍历对应的链表
			while (temp != null) {
				//key重复则覆盖
				if (temp.key.equals(key)) {
					System.out.println("key重复，将要执行覆盖操作。");
					//只是覆盖value即可，其他的值（hash、key、next）都保持不变
					temp.value = value;
					keyRepeat = true;
					break;
					
				}else {
					iterLast = temp;
					//不重复的话，继续遍历往下
					temp = temp.next;
				}
			}
			
			if (!keyRepeat) {
				//因为没有发生key覆盖，next不需要改变
				iterLast.next = newNode;
				size ++;
			}
		}
	}
	
	public V get(int key) {
		int hash = myHash(key,table.length);
		V value = null;
		
		if (table[hash] != null) {
			Node3 temp = table[hash];
			while(temp != null) {
				if (temp.key.equals(key)) {
					value = (V)temp.value;
					break;
				}
				temp = temp.next;
			}
		}
		
		return value; 
	}
	
	public int myHash(int v,int l) {
		//System.out.println(v&(l - 1));
		return v&(l - 1);
	}
	
	@Override
	public String toString() {
		//应该达成的效果：{1:ceshi1,2:ceshi2}
		StringBuilder sbu = new StringBuilder("{") ;
		//遍历数组
		for (int i = 0; i < table.length; i++) {
			Node3 temp = table[i];
			if(table[i] != null) {
				sbu.append("["+"桶"+i+"---> ");
			}
			//遍历链表
			while (temp != null) {
				sbu.append(temp.key + ":" + temp.value + ",");
				temp = temp.next;
			}
			sbu.setCharAt(sbu.length() - 1, '}');
			if(table[i] != null) {
				sbu.append("]");
			}
			
		}
		
		return sbu.toString();
	}
	
	public static void main(String[] args) {
		测试14自定义实现HashMap类02 h2 = new 测试14自定义实现HashMap类02<>();
		h2.put(1,"ceshi1");
		h2.put(17,"ceshi3");
		h2.put(2,"ceshi2");
		h2.put(2,"ceshi12");
		h2.put(32,"ceshi14");
		
		System.out.println(h2);
		System.out.println(h2.get(17));
	}
}