一个java多线程问题，求牛人指教

Java code

package test;public class SyncTest {    private int x;    private int y;    private  void setX (int i) {x=i;}    private  void setY (int i) {y=i;}    public void setXY(int i){setX(i); setY(i);}    public  boolean check() {        boolean f = (x !=y);        System.out.println("x="+x+",y="+y);        return f;    }        public static void main(String[] args) {        SyncTest st = new SyncTest();                for (int i=0; i<10; i++)        {            Thread t = new Th(i, st);            t.start();        }                while (true)        {            System.out.println(st.check());            try {                Thread.sleep(1000);            } catch (InterruptedException e) {                e.printStackTrace();            }        }    }        static class Th extends Thread    {        private int i;                SyncTest st ;                public Th(int i, SyncTest st)        {            this.i = i;            this.st = st;        }        @Override        public void run() {            while (true)            {                st.setXY(i);                java.util.Random random = new java.util.Random();                try {                    Thread.sleep(1000);                } catch (InterruptedException e) {                    e.printStackTrace();                }            }        }            }}

以上程序的执行结果如下：
x=1,y=1
false
x=2,y=2
false
x=4,y=4
false
x=5,y=1
false
x=1,y=1
false
x=1,y=3
false
x=7,y=7
false
x=1,y=6
false
x=6,y=0
false
x=3,y=7
false
x=7,y=7
false
不管x、y的值是什么，check方法返回的永远是false,这是为什么？？？

[解决办法]

Java code

//这样再试一下public void setXY(int i){        setX(i);         try{Thread.sleep(1);}catch(Exception e){e.printStackTrace();}        setY(i);    }