对象a作为参数argument在方法中使用时，如果argument在方法中赋予另一个对象的地址，则之后方法中对参数argument的操作，都不会影响到对象a.
方法中参数argument如果是对象，argument是源对象a的副本,方法执行结束，副本argument就被移出stack,在合适的时间就会被GC回收
/*2015-7-22*/
public class ReferenceTypeDemo {
public static void main(String[] args) {
Person tom = new Person("Tom", 20);
System.out.println(tom);
modify(tom);
System.out.println(tom);
} private static void modify(Person tom) {
System.out.println("modify():" + tom);
Person jack = new Person("Jack", 10);
tom = jack;
System.out.println(tom);
System.out.println("modify():" + tom);
tom.setName("Tom-modify");
System.out.println("modify():" + tom);
} } class Person {
private String name;
private int age; public Person(String name, int age) {
super();
this.name = name;
this.age = age;
} public void setName(String name) {
this.name = name;
} @Override
public String toString() {
return Integer.toHexString(hashCode()) + ";Person [name=" + name + ", age=" + age + "]";
}
}
Output:
14318bb;Person [name=Tom, age=20]
modify():14318bb;Person [name=Tom, age=20]
ca0b6;Person [name=Jack, age=10]
modify():ca0b6;Person [name=Jack, age=10]
modify():ca0b6;Person [name=Tom-modify, age=10]
14318bb;Person [name=Tom, age=20]
Tips:
hasCode()可以标识对象。Map中判断是否包含一个对象，就是使用hashCode()和Equals()来判断