blocks|key|3902872|text|你可以用runOnUIThread()包装吐司，但这不是最好的解决方案。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3902873|当发生错误时，应在catch块中设置一个布尔标志，然后只要该标志为true，就在onProgressUpdate()、onPostExecute()或具有UI访问的任何其它方法中显示适当的Toast。|3902874|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/reference/android/app/Activity.html#runOnUiThread%2528java.lang.Runnable%2529^0|4|F|4|F|0|0|X|4|14|I|1N|F|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@$9|S|A|T|1|U]]|E|$]]|$1|F|3|G|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]|$9|10|A|11|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

You could wrap the Toast in <a href="http://developer.android.com/reference/android/app/Activity.html#runOnUiThread%28java.lang.Runnable%29" rel="noreferrer"><code>runOnUIThread()</code></a> but this isn't the best solution. 
You should set a boolean flag in the catch block when an error occurs, then display an appropriate Toast in <code>onProgressUpdate()</code>, <code>onPostExecute()</code>, or any of the other methods with UI access whenever the flag is <code>true</code>.

blocks|key|4383844|text|从doInBackground返回为|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4383845|protected+String+doInBackground(String...+params){
++++//some+code
++++try{
+++++++//some+code
+++++}catch(Exception+e){
++++++++return+"Exception+Caught";
+++++}
+++++return+someValidResult;
}

protected+void+onPostExecute(String+result){
++++if(result.equalsIgnoreCase("Exception+Caught")){
+++++++//Display+Toast
++++}else{
+++++++//+//+whatever+you+wana+do+with+valid+result
++++}
}|code-block|syntax|javascript|4383846|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

return from doInBackground as

<pre><code>protected String doInBackground(String... params){
 //some code
 try{
 //some code
 }catch(Exception e){
 return "Exception Caught";
 }
 return someValidResult;
}

protected void onPostExecute(String result){
 if(result.equalsIgnoreCase("Exception Caught")){
 //Display Toast
 }else{
 // // whatever you wana do with valid result
 }
}
</code></pre>

blocks|key|4384036|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4384037|runOnUiThread(new+Runnable()+{

public+void+run()+{

++Toast.makeText(getApplicationContext(),+"Example+for+Toast",+Toast.LENGTH_SHORT).show();

+++}
});|code-block|syntax|javascript|4384038|4384039|BTW:如果您使用的是Fragments，则需要通过您的活动调用runOnUiThread(...)：|unordered-list-item|offset|length|style|CODE|4384040|4384041|getActivity().runOnUiThread(...)|4384042|entityMap^0|0|0|0|B|9|W|I|0|0|0|W|0^^$0|@$1|2|3|-4|4|5|6|S|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|T|7|@]|8|@]|9|$D|E]]|$1|F|3|-4|4|5|6|U|7|@]|8|@]|9|$]]|$1|G|3|H|4|I|6|V|7|@$J|W|K|X|L|M]|$J|Y|K|Z|L|M]]|8|@]|9|$]]|$1|N|3|-4|4|5|6|10|7|@]|8|@]|9|$]]|$1|O|3|P|4|5|6|11|7|@$J|12|K|13|L|M]]|8|@]|9|$]]|$1|Q|3|-4|4|5|6|14|7|@]|8|@]|9|$]]]|R|$]]

Write the following code where you have to show toast in <code>doInBackground()</code> method

<pre><code>runOnUiThread(new Runnable() {

public void run() {

 Toast.makeText(getApplicationContext(), "Example for Toast", Toast.LENGTH_SHORT).show();

 }
});
</code></pre>

<ul>
<li>BTW: if you are using <code>Fragments</code>, you need to call <code>runOnUiThread(...)</code> through your activity:</li>
</ul>

<code>getActivity().runOnUiThread(...)</code>

blocks|key|554323|text|您可以在方法中显示它，该方法可以访问UI线程，如onPreExecute()、onProgressUpdate()和onPostExecute()|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|554324|entityMap^0|O|E|13|I|1M|F|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|O|8|@]|D|@]|E|$]]]|G|$]]

You can display it in a method, that has access to the UI thread like <code>onPreExecute()</code>, <code>onProgressUpdate()</code> and <code>onPostExecute()</code>

blocks|key|41060|text|创建一个处理程序对象，并使用该对象执行所有Toast消息。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|41061|@Override
protected+Void+doInBackground(Void...+params)+{

++++Handler+handler=new+handler();
++++handler=++new+Handler(context.getMainLooper());
++++handler.post(+new+Runnable(){
++++++++public+void+run(){
++++++++++++Toast.makeText(context,+"Created+a+server+socket",Toast.LENGTH_LONG).show();+
++++++++}
++++});
++}|code-block|syntax|javascript|41062|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Create a handler object and execute all your Toast messages using that.

<pre><code>@Override
protected Void doInBackground(Void... params) {

 Handler handler=new handler();
 handler= new Handler(context.getMainLooper());
 handler.post( new Runnable(){
 public void run(){
 Toast.makeText(context, "Created a server socket",Toast.LENGTH_LONG).show(); 
 }
 });
 }
</code></pre>

blocks|key|3903140|text|runOnUiThread(new+Runnable()+{

public+void+run()+{

++Toast.makeText(getApplicationContext(),+"Example+for+Toast",+Toast.LENGTH_SHORT).show();

+++}
});+|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3903141|可以很好地在doInBackground()方法中显示吐司|unstyled|3903142|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>runOnUiThread(new Runnable() {

public void run() {

 Toast.makeText(getApplicationContext(), "Example for Toast", Toast.LENGTH_SHORT).show();

 }
}); 
</code></pre>

is working perfectly fine to show toast in doInBackground() method

blocks|key|3903185|text|activity.runOnUiThread(new+Runnable()+{
+public+void+run()+
+{
++++Toast.makeText(activity,+"Toast+teaxt",+Toast.LENGTH_SHORT).show();
+}
});|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3903186|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>activity.runOnUiThread(new Runnable() {
 public void run() 
 {
 Toast.makeText(activity, "Toast teaxt", Toast.LENGTH_SHORT).show();
 }
});
</code></pre>

blocks|key|554603|text|试试这段代码|type|unstyled|depth|inlineStyleRanges|entityRanges|data|554604|void+showError(final+String+err)+{
++++runOnUiThread(new+Runnable()+{
++++++++public+void+run()+{
++++++++++++Toast.makeText(downloadprogress.this,+err+%2B+"error+in+download",+Toast.LENGTH_LONG)
++++++++++++++++++++.show();
++++++++}
++++});
++}|code-block|syntax|javascript|554605|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

try this code

<pre><code>void showError(final String err) {
 runOnUiThread(new Runnable() {
 public void run() {
 Toast.makeText(downloadprogress.this, err + "error in download", Toast.LENGTH_LONG)
 .show();
 }
 });
 }
</code></pre>

blocks|key|3903215|text|如果你必须声明任何与线程相关的东西，那么它必须在runOnUiThread()方法之外，然后只有它才会被执行，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3903216|++++@Override
++++protected+String+doInBackground(String...+strings)+{
++++++++for(int+i=0;+i<10;+i%2B%2B)+{

++++++++++++runOnUiThread(new+Runnable()+{
++++++++++++++++public+void+run()+{
++++++++++++++++++++Toast.makeText(getApplicationContext(),+"Example+for+Toast+"%2Bi,+Toast.LENGTH_SHORT).show();
++++++++++++++++}
++++++++++++});

++++++++++++try+{
++++++++++++++++Thread.sleep(10);
++++++++++++}+catch+(Exception+e)+{}
++++++++}

++++++++return+"";
++++}|code-block|syntax|javascript|3903217|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you have to declare anything related to Thread, then it must be outside the runOnUiThread() method, then only it is going to execute,

<pre><code> @Override
 protected String doInBackground(String... strings) {
 for(int i=0; i&lt;10; i++) {

 runOnUiThread(new Runnable() {
 public void run() {
 Toast.makeText(getApplicationContext(), "Example for Toast "+i, Toast.LENGTH_SHORT).show();
 }
 });

 try {
 Thread.sleep(10);
 } catch (Exception e) {}
 }

 return "";
 }
</code></pre>

In one of my activities I'm using <code>AsyncTask</code>. In <code>doInBackground()</code> I'm making calls to various methods. In one of these methods I'm getting an exception, so in the catch block I want to show the error in the Toast.
I know I can use <code>Log</code>, but still I prefer Toast.
So, how can I use Toast in AsyncTask in doInBackground()?

How to show toast in AsyncTask in doInBackground

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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在我的一个活动中，我使用了AsyncTask。在doInBackground()中，我调用了各种方法。我知道我可以使用Log，但我还是更喜欢Toast。那么，如何在doInBackground()中使用AsyncTask中的Toast呢？

问如何在doInBackground中显示AsyncTask中的toast
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回答 9

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问如何在doInBackground中显示AsyncTask中的toast
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