Java手写简易版HashMap的使用(存储+查找)
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2022-07-02 09:22:35
hashmap的基本结构
package com.liuyuhe;
public class node {
int hash;
object key;...
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<table.length;++i) { //遍历链表 node temp = table[i]; while(temp!=null) { if(isfirst) { isfirst=false; sb.append(temp.key+":"+temp.value); }else { sb.append(","+temp.key+":"+temp.value); } temp=temp.next; } } sb.append("}"); return sb.tostring(); }
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<k,v> { int hash; k key; v value; node next; }
package com.liuyuhe; public class myhashmap<k,v> { 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<table.length;++i) { //遍历链表 node temp = table[i]; while(temp!=null) { if(isfirst) { isfirst=false; sb.append(temp.key+":"+temp.value); }else { sb.append(","+temp.key+":"+temp.value); } temp=temp.next; } } sb.append("}"); return sb.tostring(); } }
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