Ich bin ein neuer Android-Programmierer und in letzter Zeit haben viele meiner Projekte diesen Fehler erhalten:
07-31 23:45:19.592: ERROR/AndroidRuntime(716): java.lang.RuntimeException: Unable to start
activity ComponentInfo{com.amrit.musifind/com.amrit.musifind.Main}:
java.lang.NullPointerException
Kann mir jemand helfen, dieses Problem zu lösen?
Hier ist der gesamte Logcat-Stack-Trace:
07-31 23:45:18.512: INFO/ActivityManager(63): Starting activity: Intent {
act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000
cmp=com.amrit.musifind/.Main }
07-31 23:45:18.682: INFO/ActivityManager(63): Start proc com.amrit.musifind for activity
com.amrit.musifind/.Main: pid=716 uid=10025 gids={3003}
07-31 23:45:18.962: INFO/jdwp(716): received file descriptor 20 from ADB
07-31 23:45:19.102: DEBUG/ddm-heap(716): Got feature list request
07-31 23:45:19.572: DEBUG/AndroidRuntime(716): Shutting down VM
07-31 23:45:19.572: WARN/dalvikvm(716): threadid=3: thread exiting with uncaught
exception (group=0x4001aa28)
07-31 23:45:19.572: ERROR/AndroidRuntime(716): Uncaught handler: thread main exiting due
to uncaught exception
07-31 23:45:19.592: ERROR/AndroidRuntime(716): java.lang.RuntimeException: Unable to
start activity ComponentInfo{com.amrit.musifind/com.amrit.musifind.Main}:
java.lang.NullPointerException
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2401)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2417)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
android.app.ActivityThread.access$2100(ActivityThread.java:116)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
android.os.Handler.dispatchMessage(Handler.java:99)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
android.os.Looper.loop(Looper.java:123)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
android.app.ActivityThread.main(ActivityThread.java:4203)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
java.lang.reflect.Method.invokeNative(Native Method)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
java.lang.reflect.Method.invoke(Method.java:521)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
dalvik.system.NativeStart.main(Native Method)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): Caused by: java.lang.NullPointerException
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
com.amrit.musifind.Main.onCreate(Main.java:44)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2364)
07-31 23:45:19.592: ERROR/AndroidRuntime(716): ... 11 more
07-31 23:45:19.612: INFO/Process(63): Sending signal. PID: 716 SIG: 3
07-31 23:45:19.612: INFO/dalvikvm(716): threadid=7: reacting to signal 3
07-31 23:45:19.642: INFO/dalvikvm(716): Wrote stack trace to '/data/anr/traces.txt'
07-31 23:45:21.422: INFO/Process(716): Sending signal. PID: 716 SIG: 9
07-31 23:45:21.442: INFO/ActivityManager(63): Process com.amrit.musifind (pid 716) has
died.
07-31 23:45:21.583: WARN/UsageStats(63): Unexpected resume of com.android.launcher while
already resumed in com.amrit.musifind
07-31 23:45:21.712: WARN/InputManagerService(63): Window already focused, ignoring focus
gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@439559d0
07-31 23:45:23.482: DEBUG/AndroidRuntime(725): >>>>>>>>>>>>>> AndroidRuntime START
<<<<<<<<<<<<<<
07-31 23:45:23.482: DEBUG/AndroidRuntime(725): CheckJNI is ON
07-31 23:45:23.812: DEBUG/AndroidRuntime(725): --- registering native functions ---
07-31 23:45:23.832: INFO/jdwp(725): received file descriptor 20 from ADB
07-31 23:45:24.193: DEBUG/ddm-heap(725): Got feature list request
07-31 23:45:25.052: DEBUG/AndroidRuntime(725): Shutting down VM
07-31 23:45:25.052: DEBUG/dalvikvm(725): DestroyJavaVM waiting for non-daemon threads to
exit
07-31 23:45:25.062: DEBUG/dalvikvm(725): DestroyJavaVM shutting VM down
07-31 23:45:25.062: DEBUG/dalvikvm(725): HeapWorker thread shutting down
07-31 23:45:25.062: DEBUG/dalvikvm(725): HeapWorker thread has shut down
07-31 23:45:25.073: DEBUG/jdwp(725): JDWP shutting down net...
07-31 23:45:25.073: DEBUG/jdwp(725): +++ peer disconnected
07-31 23:45:25.073: INFO/dalvikvm(725): Debugger has detached; object registry had 1
entries
07-31 23:45:25.093: DEBUG/dalvikvm(725): VM cleaning up
07-31 23:45:25.113: DEBUG/dalvikvm(725): LinearAlloc 0x0 used 665652 of 4194304 (15%)
07-31 23:47:22.712: DEBUG/dalvikvm(104): GC freed 9173 objects / 524184 bytes in 149ms
Hier ist die 1. Aktivität: start.java
package com.amrit.musifind;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import com.amrit.musifind.R;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public abstract class start extends Activity implements OnClickListener {
Button buttonGo, buttonReset;
EditText EditTextinput;
String input = "";
String ur = "http://www.tastekid.com/ask/ws?q=";
String l = "&f=musifin2125&k=mjjlnzkyzwuz&format=JSON";
String url = "" ;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
buttonGo = (Button) findViewById(R.id.buttonGo);
buttonReset = (Button) findViewById(R.id.buttonReset);
EditTextinput = (EditText) findViewById(R.id.EditTextinput);
//Button listener
buttonReset.setOnClickListener(this);
buttonGo.setOnClickListener(this);
}
public void onClick (View src){
switch(src.getId()){
case R.id.buttonGo:
input = EditTextinput.getText().toString();
url = ur + input + l ;
Intent Main = new Intent(this, ToClass.class);
Main.putExtra("userurl", url);
startActivity(Main);
break;
case R.id.buttonReset:
EditTextinput.setText("");
break;
}
}
}
Die zweite Aktivität: Main.java
package com.amrit.musifind;
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import com.amrit.musifind.JSONfunctions;
import com.amrit.musifind.R;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class Main extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listplaceholder);
Intent intent = getIntent();
String url = intent.getExtras().getString("userurl");
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>
();
JSONObject json = JSONfunctions.getJSONfromURL(url);
try{
JSONObject earthquakes = json.getJSONObject("Similar");
JSONArray info = earthquakes.getJSONArray("Results");
for (int i = 0; i < info.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = info.getJSONObject(i);
map.put("id", String.valueOf(i));
map.put("name", "Name:" + e.getString("Name"));
map.put("type", "Type: " + e.getString("Type"));
mylist.add(map);
}
JSONArray results = json.getJSONArray("Results");
for(int i=0;i<results.length();i++){
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = results.getJSONObject(i);
map.put("id", String.valueOf(i));
map.put("name", "Name:" + e.getString("name"));
map.put("type", "Type: " + e.getString("type"));
mylist.add(map);
}
} catch(JSONException e) {
Log.e("log_tag", "Error parsing data "+e.toString());
}
ListAdapter adapter = new SimpleAdapter(this, mylist , R.layout.main,
new String[] { "name", "type" },
new int[] { R.id.item_title, R.id.item_subtitle });
setListAdapter(adapter);
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
@SuppressWarnings("unchecked")
HashMap<String, String> o = (HashMap<String, String>) lv.getItemAtPosition(position);
Toast.makeText(Main.this, "ID '" + o.get("id") + "' was clicked.",
Toast.LENGTH_SHORT).show();
}
});
}
}
Zuletzt meine Manifestdatei: AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.amrit.musifind"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="4" />
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".start" android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.start" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name= ".Main">
<intent-filter>
<action android:name="android.intent.action.Main" />
</intent-filter>
</activity>
</application>
<uses-permission android:name="android.permission.INTERNET" />
</manifest>
Jede Hilfe ist sehr willkommen, ohne dieses Problem zu lösen, kann ich meine App nicht testen!
könntest du bitte den kompletten Stacktrace posten?
– Mircea Nistor
1. August 2011 um 15:26 Uhr
Wie mache ich das? Entschuldigung, ich bin ganz neu bei Android 🙂
– Slicekick
1. August 2011 um 15:46 Uhr
Sie finden den Call-Stack in der Logcat-Ausgabe. Sie haben einen Teil davon bereits am Anfang Ihres Beitrags eingefügt (der mit der Nullzeiger-Ausnahme).
– Mircea Nistor
1. August 2011 um 15:50 Uhr
Ich habe dies erhalten, als ich versucht habe, einen Klick-Listener zuzuweisen, bevor ich eine Inhaltsansicht festgelegt habe. Wenn also vor dem Aufruf von setContentView zum Einrichten der Ansicht ein view.setOnClickListener angezeigt wird, erhalten Sie diesen Fehler. Wenn Ihr Code dies auch tut, ändern Sie einfach die Reihenfolge um zuerst die Ansicht festzulegen und dann die Zuhörer zuzuweisen.
– Damian Smith
4. Februar 2013 um 11:52 Uhr