java方法中‘值传递’不影响main方法中的实参

public class 类名 {
	public static void main(String[] arg) {
		int a = 10;
		int b = 20;
		
		AA obj = new AA();		//从AA类创建obj对象
		obj.swap(a, b);		//调用sway方法
		System.out.println("nmain方法中a，b的值");
		System.out.println("a = "+ a + "tb = " + b);	
	}
}

class AA{
	
	public void swap(int a,int b) {
		System.out.println("na和b交换前的值na = " + a + "tb = "+ b);
		int tmp = a;
		a = b;
		b = tmp;
		System.out.println("na和b交换后的值na = " + a + "tb = "+ b);
	}
}

a和b交换前的值
a = 10 b = 20

a和b交换后的值
a = 20 b = 10

main方法中a，b的值
a = 10 b = 20