java programming basic knowledge-- pass object as arguments

public class ObjArgument {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
			TestObject temp=new TestObject(3);
			TestObject temp1=new TestObject(4);
			modifyObj(temp,temp1);
			System.out.println("original obj value is not changed: "+temp.a);
	}
	public static void modifyObj(TestObject obj,TestObject obj1){
		obj=obj1;
		System.out.println("changed reference in func : "+obj.a);
		obj.modifyValue(10);
		System.out.println("changed obj in func :" + obj.a);
	}

}

<pre name="code" class="java">public class TestObject {
	public int a;
	public TestObject(int value){
		this.a=value;
	}
	public void modifyValue(int value) {
		// TODO Auto-generated method stub
		this.a=value;
	}
}

程序输出如下：

changed reference in func : 4
changed obj in func :10
original obj value is not changed: 3

总结

把对象传递给函数时，传递的是对象的引用，通过引用去修改对象的值，实参对象也会随之改变；

如果在函数中修改引用(引用到另外的对象), 函数中的引用和实参就指向不同的对象，再通过引用修改对象，就是修改的其他对象的内容，而不是实参对象的内容。