Java中HashMap怎么用

这篇文章主要介绍了Java中HashMap怎么用，具有一定借鉴价值，感兴趣的朋友可以参考下，希望大家阅读完这篇文章之后大有收获，下面让小编带着大家一起了解一下。

HashMap的基本结构

package com.liuyuhe;public class Node { int hash; Object key; Object value; Node next;}

package com.liuyuhe;public class MyHashMap { Node[] table; //位桶数组 int size; //存放键值对的个数 public MyHashMap() { table=new Node[16]; } }

put()方法存储键值对

public void put(Object key,Object value) { Node newNode = new Node(); newNode.hash=myHash(key.hashCode(),table.length); newNode.key=key; newNode.value=value; newNode.next=null; Node temp = table[newNode.hash]; Node iterLast=null; if(temp==null) { table[newNode.hash]=newNode; }else { while(temp!=null) { if(temp.key.equals(key)) { temp.value=value; return; }else { iterLast=temp; temp=temp.next; } } iterLast.next=newNode; } ++size; } public int myHash(int v,int length) { System.out.println("hash in myHash: "+(v&(length-1))); return v&(length-1); }

重写toString()方法打印Map内容

@Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append("{"); boolean isFirst=true; //遍历数组 for(int i=0;i

get()方法查找键值对

public Object get(Object key) { int hash=myHash(key.hashCode(),table.length); Object value=null; if(table[hash]!=null) { Node temp=table[hash]; while(temp!=null) { if(temp.key.equals(key)) { value=temp.value; break; }else { temp=temp.next; } } } return value; }

增加泛型（完整代码）

package com.liuyuhe;public class Node { int hash; K key; V value; Node next;}

package com.liuyuhe;public class MyHashMap { Node[] table; //位桶数组 int size; //存放键值对的个数 public MyHashMap() { table=new Node[16]; } public void put(K key,V value) { Node newNode = new Node(); newNode.hash=myHash(key.hashCode(),table.length); newNode.key=key; newNode.value=value; newNode.next=null; Node temp = table[newNode.hash]; Node iterLast=null; if(temp==null) { table[newNode.hash]=newNode; }else { while(temp!=null) { if(temp.key.equals(key)) { temp.value=value; return; }else { iterLast=temp; temp=temp.next; } } iterLast.next=newNode; } ++size; } @SuppressWarnings("unchecked") public V get(K key) { int hash=myHash(key.hashCode(),table.length); V value=null; if(table[hash]!=null) { Node temp=table[hash]; while(temp!=null) { if(temp.key.equals(key)) { value=(V)temp.value; break; }else { temp=temp.next; } } } return value; } public int myHash(int v,int length) { System.out.println("hash in myHash: "+(v&(length-1))); return v&(length-1); } @Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append("{"); boolean isFirst=true; //遍历数组 for(int i=0;i

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