问题
These are created using Android Studio similar to How to modify dummy content in android master/detail activity?. I changed the static method under dummyContent into below:
public void fetchData() {
// Add some sample items.
for (int i = 1; i <= COUNT; i++) {
addItem(createDummyItem(i));
}
Authenticator.setDefault(new Authenticator() {
@Override
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(
DummyContent.UNAME, DummyContent.PASSWORD.toCharArray());
}
});
try {
DummyContentRegistry registry = new XMLDummyContentParser(DummyContent.url).parse();
for (DummyContent.DummyItem t: registry.getTeachers()) {
DummyContent.addItem(t);
}
} catch (Exception e) {
fail("Exception should not have been thrown");
}
}
while above passed the test:
public class DummyContentRegistryTest {
@Before
public void buildRegistry() {}
@Test
public void testFetchData() {
Assert.assertEquals(0,DummyContent.ITEMS.size());
new DummyContent().fetchData();
Assert.assertEquals(27,DummyContent.ITEMS.size());// two more items are added through parsing xml on a website
}
}
However when I call the method under MainActivity.onCreate it failed "Exception should not have been thrown". Why? Here's an example of failing call
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (DummyContent.ITEMS.isEmpty()) {
new DummyContent().fetchData();
}
......
}
I don't know if the problem is similar to calling non-static method in static method in Java but I've obviously tried the way most of them agreed.
[ 07-25 04:04:56.442 23983:24025 D/ ]
HostConnection::get() New Host Connection established 0x7f1b57910500, tid 24025
07-25 04:04:56.460 23983-24025/*****private*****.myapplication I/OpenGLRenderer: Initialized EGL, version 1.4
07-25 04:04:56.873 23983-23983/*****private*****.myapplication I/Choreographer: Skipped 32 frames! The application may be doing too much work on its main thread.
07-25 04:05:07.474 23983-23983/*****private*****.myapplication W/System.err: java.io.IOException: Couldn't open *****private*****
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at org.apache.harmony.xml.ExpatParser.openUrl(ExpatParser.java:755)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at org.apache.harmony.xml.ExpatReader.parse(ExpatReader.java:292)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at javax.xml.parsers.SAXParser.parse(SAXParser.java:390)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at javax.xml.parsers.SAXParser.parse(SAXParser.java:266)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at *****private*****.myapplication.dummy.XMLDummyContentParser.parse(XMLDummyContentParser.java:33)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at *****private*****.myapplication.dummy.DummyContent.fetchData(DummyContent.java:53)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at *****private*****.myapplication.MainActivity.onCreate(MainActivity.java:52)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at android.app.Activity.performCreate(Activity.java:6237)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at android.app.ActivityThread.-wrap11(ActivityThread.java)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at android.os.Handler.dispatchMessage(Handler.java:102)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at android.os.Looper.loop(Looper.java:148)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at android.app.ActivityThread.main(ActivityThread.java:5417)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at java.lang.reflect.Method.invoke(Native Method)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: Caused by: android.os.NetworkOnMainThreadException
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1273)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at java.net.InetAddress.lookupHostByName(InetAddress.java:431)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at java.net.InetAddress.getAllByNameImpl(InetAddress.java:252)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at java.net.InetAddress.getAllByName(InetAddress.java:215)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.Network$1.resolveInetAddresses(Network.java:29)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:188)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.http.RouteSelector.nextProxy(RouteSelector.java:157)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:100)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.http.HttpEngine.createNextConnection(HttpEngine.java:357)
07-25 04:05:07.475 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.http.HttpEngine.nextConnection(HttpEngine.java:340)
07-25 04:05:07.476 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:330)
07-25 04:05:07.476 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:248)
07-25 04:05:07.476 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:433)
07-25 04:05:07.476 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:384)
07-25 04:05:07.476 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:231)
07-25 04:05:07.476 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.huc.DelegatingHttpsURLConnection.getInputStream(DelegatingHttpsURLConnection.java:210)
07-25 04:05:07.476 23983-23983/*****private*****.myapplication W/System.err: at com.android.okhttp.internal.huc.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java)
07-25 04:05:07.476 23983-23983/*****private*****.myapplication W/System.err: at org.apache.harmony.xml.ExpatParser.openUrl(ExpatParser.java:753)
07-25 04:05:07.476 23983-23983/*****private*****.myapplication W/System.err: ... 18 more
07-25 04:05:07.483 23983-23983/*****private*****.myapplication D/AndroidRuntime: Shutting down VM
07-25 04:05:07.484 23983-23983/*****private*****.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
Process: ******private*******, PID: 23983
java.lang.RuntimeException: Unable to start activity ComponentInfo{******private*******.myapplication.MainActivity}: java.lang.IllegalStateException: Already attached
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.IllegalStateException: Already attached
at android.support.v4.app.FragmentManagerImpl.attachController(FragmentManager.java:2126)
at android.support.v4.app.FragmentController.attachHost(FragmentController.java:104)
at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:313)
at android.support.v7.app.AppCompatActivity.onCreate(AppCompatActivity.java:85)
at *****private*****.myapplication.MainActivity.onCreate(MainActivity.java:55)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
回答1:
The Exception e, which you catch may contain useful information on what exactly went wrong. Do e.printStackTrace(); inside your catch-block to print all available information to the standard output.
If that does not help you solve the problem post the stacktrace here.
回答2:
You cannot manipulate UI thread from background thread thats why you are getting this error.
ClassName.this.runOnUiThread(new Runnable() {
public void run() {
//Do something on UiThread
// enclose your UI manipulated code here in these braces.
}
});
来源：https://stackoverflow.com/questions/38565911/failed-to-call-a-dynamic-method-in-a-static-context