[Java] 容器-05 Map 方法

TestMap

package com.bjsxt.p7;

import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

public class TestMap {
    public static void main(String[] args) {
        Map m1 = new HashMap();
        Map m2 = new TreeMap();
        
        m1.put("one", new Integer(1));
        m1.put("two", new Integer(2));
        m1.put("three", new Integer(3));
        
        m2.put("A", new Integer(1));
        m2.put("B", new Integer(2));
        
        System.out.println(m1.size()); // 3
        System.out.println(m1.containsKey("one"));  // true
        
        System.out.println(m2.containsValue(new Integer(1))); // 包含 value , true，
        
        System.out.println("---------This is halving line--------------");
        
        if (m1.containsKey("two" )) {
            int i = (((Integer) m1.get("two")).intValue()); // 不用泛型，就是麻烦
            System.out.println(i);
        }
        Map m3 = new HashMap(m1);
        System.out.println(m3);
        m3.putAll(m2);
        System.out.println(m3);
    }
}

输出 ：

3
true
true
---------This is halving line--------------
2
{two=2, one=1, three=3}
{two=2, A=1, B=2, one=1, three=3}

TestMap2

package com.bjsxt.p7;

import java.util.*;

public class TestMap2 {
    public static void main(String args[]) {
        Map m1 = new HashMap();
        Map m2 = new TreeMap();

        m1.put("one", 1);
        m1.put("two", 2);
        m1.put("three", 3);

        m2.put("B", 1);
        m2.put("A", 2);

        show(m1.size());  // 3
        show(m1.containsKey("one")); // true
        
        show(m2.containsValue(1));   // true

        if (m1.containsKey("two")) {
            int i = (Integer) m1.get("two");
            show(i); // 2
        }
        
        show(m1);
        show(m2);
        
        Map m3 = new HashMap(m1);
        m3.putAll(m2);
        System.out.println(m3);
    }
    public static void show(Object o) {
    	System.out.println(o);
    }
}

输出 ：

3
true
true
2
{two=2, one=1, three=3}
{A=2, B=1}
{two=2, A=2, B=1, one=1, three=3}