L’application Android ne peut pas démarrer l’activité componentinfo

Je suis un nouveau programmeur Android et récemment, beaucoup de mes projets ont reçu cette erreur:

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

Quelqu’un peut-il m’aider à résoudre ce problème?

Voici la trace complète de la stack logcat:

 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

Voici la 1ère activité: 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; Ssortingng input = ""; Ssortingng ur = "http://www.tastekid.com/ask/ws?q="; Ssortingng l = "&f=musifin2125&k=mjjlnzkyzwuz&format=JSON"; Ssortingng 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().toSsortingng(); 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; } } }

La deuxième activité: 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(); Ssortingng url = intent.getExtras().getSsortingng("userurl"); ArrayList<HashMap> mylist = new ArrayList<HashMap> (); 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 map = new HashMap(); JSONObject e = info.getJSONObject(i); map.put("id", Ssortingng.valueOf(i)); map.put("name", "Name:" + e.getSsortingng("Name")); map.put("type", "Type: " + e.getSsortingng("Type")); mylist.add(map); } JSONArray results = json.getJSONArray("Results"); for(int i=0;i<results.length();i++){ HashMap map = new HashMap(); JSONObject e = results.getJSONObject(i); map.put("id", Ssortingng.valueOf(i)); map.put("name", "Name:" + e.getSsortingng("name")); map.put("type", "Type: " + e.getSsortingng("type")); mylist.add(map); } }catch(JSONException e) { Log.e("log_tag", "Error parsing data "+e.toSsortingng()); } ListAdapter adapter = new SimpleAdapter(this, mylist , R.layout.main, new Ssortingng[] { "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 o = (HashMap) lv.getItemAtPosition(position); Toast.makeText(Main.this, "ID '" + o.get("id") + "' was clicked.", Toast.LENGTH_SHORT).show(); } }); } }

Enfin, mon fichier manifeste: AndroidManifest.xml

Toute aide est très appréciée, sans résoudre ce problème, je ne peux pas tester mon application!

Votre exception de pointeur nul semble être sur cette ligne:

 Ssortingng url = intent.getExtras().getSsortingng("userurl");

parce que intent.getExtras() renvoie null lorsque l’intention n’a pas de bonus.

Vous devez réaliser que ce morceau de code:

 Intent Main = new Intent(this, ToClass.class); Main.putExtra("userurl", url); startActivity(Main);

ne commence pas l’activité que vous avez écrite dans Main.java, il va tenter de démarrer une activité appelée ToClass et si cela n’existe pas, votre application se bloque.

En outre, "android.intent.action.start" n’existe pas, le manifeste devrait donc ressembler davantage à:

J’espère que cela corrige certains des problèmes que vous rencontrez, mais je vous suggère fortement de consulter des didacticiels “de mise en route” pour le développement android et de construire à partir de là.