安卓 TextView setText 无效

在activity_user.xml中，有一个TextView<TextView
                android:id="@+id/txtUserId"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="NULL"
                />然后在User.java中
public static TextView tv1=null;
    public static TextView tv2=null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_user);
        tv1=(TextView) findViewById(R.id.txtUserId);
        tv2=(TextView) findViewById(R.id.txtUserNickname);
        //tv1.setText("66666");
        //setUser("管理员");
        SildingFinishLayout mSildingFinishLayout = (SildingFinishLayout) findViewById(R.id.sildingFinishLayout);
        mSildingFinishLayout
                .setOnSildingFinishListener(new SildingFinishLayout.OnSildingFinishListener() {                    @Override
                    public void onSildingFinish() {
                        User.this.finish();
                    }
                });        mSildingFinishLayout.setTouchView(mSildingFinishLayout);    }我在另外一个java文件Login.java中 有个登录函数，登录成功就会执行User.tv1.setText(id);//这个id是个String 对象 并且不是null
然而这句代码并没有起到作用，并没有改变txtUserId的显示值，求大神解答。。在线等，需要哪些代码立即补充！