[Java] 容器-05 Map 方法

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);
}
}

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

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);
}
}

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