java的值传递

@Test
    public void TestCollection() {
	User user = new User();
	user.setUsername("Tom");
	
	List<User> ulist = new ArrayList<User>();
	ulist.add(user);

	for (User u : ulist) {
	    u.setUsername("TomCat");
	}

	for (User u : ulist) {
	    System.out.println(u.getUsername());
	}
    }
    

 

class User {
    private String username;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }
}

 

运行结果：

 

TomCat

 

    @Test
    public void TestIntCollection() {
	Integer x = new Integer(1);
	
	List<Integer> ilist = new ArrayList<Integer>();
	ilist.add(x);

	for (Integer i : ilist) {
	    i = 25;
	}

	for (Integer i : ilist) {
	    System.out.println(i);
	}
    }

 运行结果：

1