Question

我已经设法让它在按下对话框后运行到点，它运行主UI，但最终在我移动到另一个EditText后崩溃了。我不知道如何使用onProgressUpdate（）来确保相应地禁用我的EditText。

我正在寻找的是，如果用户点击大字符，我希望程序使用While循环检查ToggleButton条件。如果它仍然打开，我希望它基本上检查EditText焦点并有一些SetOnFocusChangeListener（）;它给我一个错误说Only the original thread that created a view hierarchy can touch its views.

这是我在onCreate（）中的主要类：

         //Row 1-4 EditText
         row1TextField = (EditText) findViewById(R.id.row1);
         row2TextField = (EditText) findViewById(R.id.row2);
         row3TextField = (EditText) findViewById(R.id.row3);
         row4TextField = (EditText) findViewById(R.id.row4);

        //ToggleButton
        toggleButton = (ToggleButton) findViewById(R.id.toggle1);


        AlertDialog.Builder characterChoose = new AlertDialog.Builder(context);
        characterChoose.setTitle("Character Input Option");
        characterChoose.setMessage("Please choose the option the below").setCancelable(false)
        .setPositiveButton("Large Character", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {


                toggleButton.setTextOn("LARGE");
                toggleButton.setChecked(true);
                backgroundThread bckgnd = new backgroundThread();
                bckgnd.execute();





            }

这是我的AsyncTask类：

private class backgroundThread extends AsyncTask<Boolean, Boolean, Boolean>{

        //Run on background thread.
        @Override
        protected Boolean doInBackground(Boolean... params) {
            while(toggleButton.isChecked())
            {
                if(row1TextField.isFocused())
                {
                    row2TextField.setEnabled(false);
                }

                row2TextField.setOnFocusChangeListener(new OnFocusChangeListener()
                {

                    @Override
                    public void onFocusChange(View textfield3, boolean isFocus) {
                        if(textfield3.isFocused())
                        {
                            row3TextField.setEnabled(false);
                        }

                    }

                });

                row3TextField.setOnFocusChangeListener(new OnFocusChangeListener()
                {

                    @Override
                    public void onFocusChange(View textfield3, boolean isFocus) {
                        if(textfield3.isFocused())
                        {
                            row4TextField.setEnabled(false);
                        }

                    }

                });

        }
            return null;

    }

logcat的

01-03 07:54:17.179: E/AndroidRuntime(4871): FATAL EXCEPTION: AsyncTask #1
01-03 07:54:17.179: E/AndroidRuntime(4871): java.lang.RuntimeException: An error occured while executing doInBackground()
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.os.AsyncTask$3.done(AsyncTask.java:299)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at java.lang.Thread.run(Thread.java:856)
01-03 07:54:17.179: E/AndroidRuntime(4871): Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4888)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.view.ViewRootImpl.invalidateChildInParent(ViewRootImpl.java:975)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.view.ViewGroup.invalidateChild(ViewGroup.java:4125)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.view.View.invalidate(View.java:10521)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.widget.TextView.invalidateDrawable(TextView.java:4849)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.graphics.drawable.DrawableContainer.invalidateDrawable(DrawableContainer.java:250)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.graphics.drawable.Drawable.invalidateSelf(Drawable.java:382)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.graphics.drawable.Drawable.setVisible(Drawable.java:578)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.graphics.drawable.DrawableContainer.selectDrawable(DrawableContainer.java:307)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.graphics.drawable.StateListDrawable.onStateChange(StateListDrawable.java:106)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.graphics.drawable.Drawable.setState(Drawable.java:494)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.view.View.drawableStateChanged(View.java:14372)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.widget.TextView.drawableStateChanged(TextView.java:3381)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.view.View.refreshDrawableState(View.java:14386)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.view.View.setEnabled(View.java:5733)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.widget.TextView.setEnabled(TextView.java:1402)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at com.example.dotmatrixledpanel.startPage2$backgroundThread.doInBackground(startPage2.java:313)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at com.example.dotmatrixledpanel.startPage2$backgroundThread.doInBackground(startPage2.java:1)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
01-03 07:54:17.179: E/AndroidRuntime(4871):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
01-03 07:54:17.179: E/AndroidRuntime(4871):     ... 5 more

所以我想知道，我应该在onProgressUpdate方法中添加什么，还是应该使用Runnable？

Answer 1

您无法在异步任务的doInBackground（）方法中对UI进行更改。为此，您必须使用异步任务的onPostExecute（）方法。所以你的doInBackground（）应该返回一个布尔值或你想要的东西，这样你就可以在onPostExecute（）方法中改变UI。

Answer 2

不允许来自doInBackground()的UI触摸。首先检查AsyncTask文档：http://developer.android.com/reference/android/os/AsyncTask.html

异步任务由在a上运行的计算定义后台线程，其结果发布在UI线程上。

如果您需要在UI端更新任何内容，则需要在onPreExecute()或onPostExecute()中执行此操作。

修改

我没有看到任何理由在您的代码中使用AsyncTask。

带有Toggle Button和EditText的AsyncTask doInBackground（）

2 个答案: