JAVAリファレンス伝達

public class TestAppend {
        public static void change(StringBuffer x,StringBuffer y)
        {
                x.append(y);           //x-->AB
	        	x = y;         //x  y-->B
                System.out.println(x);//x-->B
                System.out.println(y);//y-->B
        }
        public static void main(String [] args)
        {
                StringBuffer a = new StringBuffer("A");//a-->A
                StringBuffer b = new StringBuffer("B");//b-->B
                change(a,b);
                System.out.println(a);//a-->AB
                System.out.println(b);//b-->B
        }
}

印刷結果:
B
B
AB
B