untitled1.java

来自「有关java编程的课件及附上有关的源代码」· Java 代码 · 共 15 行

package SG7.Example6;
import java.util.HashMap;
class Untitled1 {
    public static void main(String[] args) {
        HashMap map=new HashMap();
        map.put(null,"zhangsan");
        map.put(new Integer(2),"lisi");
        map.put(new Integer(3),"wanger");
        map.put(null,"lisi");
        System.out.println(map.get(null));
        map.size();

    }
}