Question

我似乎无法让这个工作，在progressDialog完成后显示如何显示警告对话框？

这是一些相关的代码：

progressDialog = ProgressDialog.show(MainActivity.this, "", "Loading...");

        new Thread() {
            public void run() {
                try{
                    initializer();
                } catch (Exception e) {
                    Log.e("tag", e.getMessage());
                }
                progressDialog.dismiss();
                SharedPreferences welcome_pref = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
                welcome = welcome_pref.getString("getwelcome", "null");

                if (welcome.equals("no")) {

                }else{
                    AlertDialog welcome = new AlertDialog.Builder(MainActivity.this).show();
                    welcome.setContentView(R.layout.welcome);
                    welcome_pref = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
                    SharedPreferences.Editor welc = welcome_pref.edit();
                    welc.putString("getwelcome", "no");
                    welc.commit();
                }
            }
        }.start();
    }

    private void initializer() {
        startMoving = (ImageView) findViewById(R.id.imMove);
        aboutApp = (ImageView) findViewById(R.id.imAbout);
        devSite = (ImageView) findViewById(R.id.imDevSite);
        movingTips = (ImageView) findViewById(R.id.imTips);
        rateApp = (ImageView) findViewById(R.id.imRate);

        start = (EditText) findViewById(R.id.etFrom);
        end = (EditText) findViewById(R.id.etTo);

        startMoving.setOnClickListener(this);
        aboutApp.setOnClickListener(this);
        devSite.setOnClickListener(this);
        movingTips.setOnClickListener(this);
        rateApp.setOnClickListener(this);

        tvabout = (TextView) findViewById(R.id.tvabout);
        tvstartmove = (TextView) findViewById(R.id.tvStart);
        tvrate = (TextView) findViewById(R.id.tvRate);
        tvdevelop = (TextView) findViewById(R.id.tvDev);
        tvmovetips = (TextView) findViewById(R.id.tvTips);

        tvabout.setShadowLayer(30, 0, 0, 0xff000000);
        tvstartmove.setShadowLayer(30, 0, 0, 0xff000000);
        tvrate.setShadowLayer(30, 0, 0, 0xff000000);
        tvdevelop.setShadowLayer(30, 0, 0, 0xff000000);
        tvmovetips.setShadowLayer(30, 0, 0, 0xff000000);

        checklistitem();

    }

    private void checklistitem() {
        SharedPreferences createlistitem_pref = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
        checkitem = createlistitem_pref.getString("getcheck", "null");

        if (checkitem.equals("no")) {

        }else{
            SQLHandler checkitemstat = new SQLHandler(MainActivity.this);
            checkitemstat.open();
            checkitemstat.createList();
            checkitemstat.close();
            SharedPreferences setitem_pref = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
            SharedPreferences.Editor setcheck = setitem_pref.edit();
            setcheck.putString("getcheck", "no");
            setcheck.commit();
        }
    }
}

我收到错误说Can't create handler inside thread that has not called Looper.prepare()我知道导致此错误但是我不知道如何解决此问题。

这行代码导致了这一点。

                progressDialog.dismiss();
                SharedPreferences welcome_pref = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
                welcome = welcome_pref.getString("getwelcome", "null");

                if (welcome.equals("no")) {

                }else{
                    AlertDialog welcome = new AlertDialog.Builder(MainActivity.this).show();
                    welcome.setContentView(R.layout.welcome);
                    welcome_pref = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
                    SharedPreferences.Editor welc = welcome_pref.edit();
                    welc.putString("getwelcome", "no");
                    welc.commit();
                }

Answer 1

您无法更新线程内的UI。只有通过主线程才能更新UI，您必须使用处理程序。或者你可以这样做

runOnUiThread(new Runnable() {

                @Override
                public void run() {
                    // TODO Auto-generated method stub
                     progressDialog.dismiss();
 AlertDialog welcome = new AlertDialog.Builder(MainActivity.this).show();
                    welcome.setContentView(R.layout.welcome);
                    welcome_pref = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
                    SharedPreferences.Editor welc = welcome_pref.edit();
                    welc.putString("getwelcome", "no");
                    welc.commit();
                }
            });

Answer 2

在runonUiThread中添加警报对话框显示代码，

this.runOnUiThread(new Runnable() {

                public void run() {
                    // TODO Auto-generated method stub

                }
            });

像这样，

}else{

 MainActivity.this.runOnUiThread(new Runnable() {

                public void run() {
                      AlertDialog welcome = new AlertDialog.Builder(MainActivity.this).show();
            welcome.setContentView(R.layout.welcome);
                }
            });


                    welcome_pref = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
                    SharedPreferences.Editor welc = welcome_pref.edit();
                    welc.putString("getwelcome", "no");
                    welc.commit();
                }

正如此处建议的答案之一所示，您无法从工作线程更新UI。更新任何UI时，您必须处于UI线程中。

因此，您需要使用处理程序或runonUiThread来执行此操作。但是由于runOnUiThread内部使用处理程序，它应该可以帮到你。

Answer 3

SharedPreferences welcome_pref = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
                welcome = welcome_pref.getString("getwelcome", "null");

                if (welcome.equals("no")) {

                }else{
                    AlertDialog welcome = new AlertDialog.Builder(MainActivity.this).show();
                    welcome.setContentView(R.layout.welcome);
                    welcome_pref = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
                    SharedPreferences.Editor welc = welcome_pref.edit();
                    welc.putString("getwelcome", "no");
                    welc.commit();
                }

在Thread.

之外执行此代码段

在ProgressDialog关闭后显示alertDialog

3 个答案: