int i = (Integer)m1.get("two");为什么要强制转换？m1.get("two");得到的本来就是Integer对象啊！怎么还要转换？
import java.util.*;
public class TestMap {
public static void main(String args[]) {
Map m1 = new HashMap();
m1.put("one", 1);//自动打包，注意与上面代码的区别
m1.put("two", 2);
m1.put("three", 3);
System.out.println(m1)
if(m1.containsKey("two")) {
int i = (Integer)m1.get("two");//自动解包
System.out.println(i);
}
}
}
import java.util.*;
public class TestMap {
public static void main(String args[]) {
Map m1 = new HashMap();
m1.put("one", 1);//自动打包，注意与上面代码的区别
m1.put("two", 2);
m1.put("three", 3);
System.out.println(m1)
if(m1.containsKey("two")) {
int i = (Integer)m1.get("two");//自动解包
System.out.println(i);
}
}
}
