android-Android Handler更新界面出錯,

Android Handler更新界面出錯,

    Handler handler = new Handler() {
    public void handleMessage(Message msg) {
        super.handleMessage(msg);
        ReturnShow.setText(sMsg);//ReturnShow是一個EditText 錯誤在這裡
        ReturnShow.setSelection(ReturnShow.length());
    }
};

class ReadThread extends Thread {
    public void run() {
        sMsg = "...";
        handler.sendMessage(handler.obtainMessage());
    }
}

代碼如上, setText那裡每次都要出錯, 是什麼原因? 附上錯誤信息

最佳回答：

RerurnShow為null
 ReturnShow = (EditText) findViewById(R.id.ResultShow);這句裡面的ID搞錯了,弄成一個非當前Activity的ID;

太粗心了