我注意到之前已经问过这个问题，我尝试了一些建议但没有成功。这可能是一个拼写错误或范围问题，但我找不到问题。正在发送引号，只有意图调用不起作用时才能看到吐司。
我的QuoteFormActivity.java的一部分
private class AsyncHttpPost extends AsyncTask<String, Void, String>
{
/*
Context context;
private AsyncHttpPost(Context context) {
this.context = context.getApplicationContext();
}
*/
@Override
protected String doInBackground(String... params)
{
BufferedReader inBuffer = null;
String url = "http://www.mydomain.com/submitted_quotes.php";
String result = "fail";
try {
HttpClient httpClient = new DefaultHttpClient();
HttpPost request = new HttpPost(url);
List<NameValuePair> postParameters = new ArrayList<NameValuePair>();
postParameters.add(new BasicNameValuePair("text_quote", params[0]));
postParameters.add(new BasicNameValuePair("text_user", params[1]));
UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(
postParameters);
request.setEntity(formEntity);
httpClient.execute(request);
result="got it";
} catch(Exception e) {
// Do something about exceptions
result = e.getMessage();
} finally {
if (inBuffer != null) {
try {
inBuffer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return result;
}
protected void onPostExecute(String result)
{
Toast toast = Toast.makeText(QuoteFormActivity.this, result, Toast.LENGTH_LONG);
toast.show();
//Log.d("test_app","httppost thingy from private class: "+result);
Intent myIntent = new Intent(QuoteFormActivity.this, DisplayQuoteActivity.class);
//view.getContext().startActivity(myIntent);
startActivity(myIntent);
super.onPostExecute(result);
//startActivity(new Intent(context, DisplayQuoteActivity.class));
}
}
[编辑（评论太长）]这是清单中的活动
<activity
android:name="com.mydomain.quotes.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.mydomain.quotes.DisplayQuoteActivity"
android:label="@string/title_activity_display_quote" >
</activity>
<activity
android:name="com.mydomain.quotes.QuoteFormActivity"
android:label="@string/title_activity_quote_form"
>
</activity>
编辑堆栈跟踪？
12-17 17:23:55.101: D/test_app(1554): Show Send Quote Page
12-17 17:23:55.981: I/Choreographer(1554): Skipped 75 frames! The application may be doing too much work on its main thread.
12-17 17:24:16.091: I/Choreographer(1554): Skipped 32 frames! The application may be doing too much work on its main thread.
12-17 17:24:23.491: D/test_app(1554): Send quote form: test Afz: stack
12-17 17:24:23.902: D/dalvikvm(1554): GC_CONCURRENT freed 184K, 10% free 3059K/3364K, paused 73ms+113ms, total 277ms
12-17 17:24:24.542: D/test_app(1554): httppost thingy from private class: got it
12-17 17:24:24.981: D/AndroidRuntime(1554): Shutting down VM
12-17 17:24:25.021: W/dalvikvm(1554): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
12-17 17:24:25.081: E/AndroidRuntime(1554): FATAL EXCEPTION: main
12-17 17:24:25.081: E/AndroidRuntime(1554): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mydomain.quotes/com.mydomain.quotes.DisplayQuoteActivity}: java.lang.NullPointerException
12-17 17:24:25.081: E/AndroidRuntime(1554): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
12-17 17:24:25.081: E/AndroidRuntime(1554): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
12-17 17:24:25.081: E/AndroidRuntime(1554): at android.app.ActivityThread.access$600(ActivityThread.java:141)
12-17 17:24:25.081: E/AndroidRuntime(1554): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
12-17 17:24:25.081: E/AndroidRuntime(1554): at android.os.Handler.dispatchMessage(Handler.java:99)
12-17 17:24:25.081: E/AndroidRuntime(1554): at android.os.Looper.loop(Looper.java:137)
12-17 17:24:25.081: E/AndroidRuntime(1554): at android.app.ActivityThread.main(ActivityThread.java:5041)
12-17 17:24:25.081: E/AndroidRuntime(1554): at java.lang.reflect.Method.invokeNative(Native Method)
12-17 17:24:25.081: E/AndroidRuntime(1554): at java.lang.reflect.Method.invoke(Method.java:511)
12-17 17:24:25.081: E/AndroidRuntime(1554): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
12-17 17:24:25.081: E/AndroidRuntime(1554): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
12-17 17:24:25.081: E/AndroidRuntime(1554): at dalvik.system.NativeStart.main(Native Method)
12-17 17:24:25.081: E/AndroidRuntime(1554): Caused by: java.lang.NullPointerException
12-17 17:24:25.081: E/AndroidRuntime(1554): at com.mydomain.quotes.DisplayQuoteActivity.onCreate(DisplayQuoteActivity.java:30)
12-17 17:24:25.081: E/AndroidRuntime(1554): at android.app.Activity.performCreate(Activity.java:5104)
12-17 17:24:25.081: E/AndroidRuntime(1554): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
12-17 17:24:25.081: E/AndroidRuntime(1554): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
12-17 17:24:25.081: E/AndroidRuntime(1554): ... 11 more
btw：在应用程序设计中，这是一个“谢谢你提交”的好方法，只需将用户重定向到选定的活动。
答案 0 :(得分：1)
问题似乎是您尝试启动活动的方式。尝试将onPostExecute更改为：
protected void onPostExecute(String result)
{
Toast toast = Toast.makeText(QuoteFormActivity.this, result, Toast.LENGTH_LONG);
toast.show();
QuoteFormActivity.this.startActivity(new Intent(QuoteFormActivity.this, BuiltInCamera.class));
super.onPostExecute(result);
}
答案 1 :(得分：1)
更详细地阅读您的例外情况，您会发现：
DisplayQuoteActivity.onCreate(DisplayQuoteActivity.java:30) NullPointerException
只需检查第30行的DisplayQuoteActivity，您就会发现Android未创建新活动的问题。 startActivity代码工作正常！