`import java.util.HashMap;
public class Demo9{
public static void main(String[] args){
HashMap<Integer,String> m1 = new HashMap<>();
HashMap<Integer,String> m2 = new HashMap<Integer,String>(){};
HashMap<Integer,String> m3 = new HashMap<Integer,String>(){
{
put(1,"name");
put(2,"age");
put(3,"weight");
}
};
System.out.println(m3.get(3));
}
}`
map1是一個普通的HashMap實例,但map2是一個匿名類實例,只是該匿名類繼承自HashMap。map3也是一個繼承自HashMap的匿名類實例,並且添加了static代碼塊來初始化數據
