HashMap 和TreeMap的比较-优快云博客

本文链接：https://blog.youkuaiyun.com/iteye_206/article/details/82041274

本文通过两个示例程序，展示了Java中HashMap与TreeMap的区别。HashMap提供无序的数据存储，而TreeMap则按关键字自动排序，但后者因排序操作而性能略逊一筹。

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[b]HashMap 和TreeMap的比较[/b]
与Java相关信息
HashMap的代码为：

import java.util.*; 
public class hashmap { 
    Map calendar = new HashMap(); 
    public hashmap(String d[],String i[]){ 
        for(int j=0;j<d.length;j++){ 
            calendar.put(d[j], i[j]); 
        } 
    } 
    public static void main(String[] args) { 
        String [] dates = {"10/4","05/7","12/7","01/5"}; 
        String [] items = {"Z","Y","X","C"}; 
        hashmap example = new hashmap(dates,items); 
        Set mapping = example.calendar.entrySet(); 
        System.out.println("map= "+example.calendar); 
        System.out.println("Object\tkey\tvalue"); 
        for(Iterator it = mapping.iterator();it.hasNext();){ 
            Map.Entry me = (Map.Entry)it.next(); 
            Object ok = me.getKey(); 
            Object ov = me.getValue(); 
            System.out.print(me+"\t"); 
            System.out.print(ok+"\t"); 
            System.out.println(ov); 
        } 
    } 

}

HashTree的代码：

import java.util.*; 
public class hashmap { 
    Map calendar = new TreeMap(); 
    public hashmap(String d[],String i[]){ 
        for(int j=0;j<d.length;j++){ 
            calendar.put(d[j], i[j]); 
        } 
    } 
    public static void main(String[] args) { 
        String [] dates = {"10/4","05/7","12/7","01/5"}; 
        String [] items = {"Z","Y","X","C"}; 
        hashmap example = new hashmap(dates,items); 
        Set mapping = example.calendar.entrySet(); 
        System.out.println("map= "+example.calendar); 
        System.out.println("Object\tkey\tvalue"); 
        for(Iterator it = mapping.iterator();it.hasNext();){ 
            Map.Entry me = (Map.Entry)it.next(); 
            Object ok = me.getKey(); 
            Object ov = me.getValue(); 
            System.out.print(me+"\t"); 
            System.out.print(ok+"\t"); 
            System.out.println(ov); 
        } 
    } 

}