android - activity之间传递参数回到主函数时，执行方法onActivityResult中getBundleExtra报错为空指针

Question

login.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            Intent loginIntent = new Intent(login.this,MainActivity.class);
            number = SNumber.getText().toString();
            password = PassWord.getText().toString();
            xmlThread xmlThread = new xmlThread(url,number,password,loginIntent);
            xmlThread.start();setResult(Activity.RESULT_OK,loginIntent);
            finish();
        }
    });
    xmlThread中的将数据通过intent传递
    userDataList = updatas;
        intent.putExtra("imageUrl",userDataList.get(0).getImageUrl());
        intent.putExtra("SName", userDataList.get(0).getSName());
        intent.putExtra("SNumber", userDataList.get(0).getSNumber());
        intent.putExtra("SClass", userDataList.get(0).getSClass());
        Log.e("main",userDataList.get(0).getImageUrl());
        主函数中点击事件，进入登录界面。
        imageButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            startActivityForResult(new Intent(MainActivity.this,login.class), REQUSET);
        }
    });
    获取Intent中的参数
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (data!=null) {
        switch (requestCode) {
            case REQUSET:
                imageUrl = data.getBundleExtra("imageUrl").toString();//从这行就开始报错了
                new HttpImageButton(imageUrl, handler, imageButton);
                TName = data.getBundleExtra("SName").toString();
                TNumber = data.getBundleExtra("SNumber").toString();
                TClass = data.getBundleExtra("SClass").toString();
                Toast.makeText(this, imageUrl + TName + TNumber + TClass, Toast.LENGTH_LONG).show();
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                        name.setText("1");
                        SNumber.setText("2");
                        SClass.setText("3");
                    }
                });
                break;
            default:
                break;
        }
    }
}
错误提示为java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { cmp=com.tjapp.login1_2/.MainActivity }} to activity {com.tjapp.login1_2/com.tjapp.login1_2.MainActivity}: java.lang.NullPointerException，报出来一个空指针。![图片描述][1]

Answer 1

看起来像是线程同步问题
xmlThread.start();
setResult(Activity.RESULT_OK,loginIntent);
xmlThread可能都还没执行起来，就已经setResult了，intent中的imageUrl还没初始化并赋值，所以报空指异常。

Answer 2

代码贴的太凌乱了。提供一种思路，注意MainActivity的启动模式，假如是单实例的话，startActivityForResult会立即返回到onActivityResult