您好我目前正在学习如何使用服务和通知在android和我面临NullPointerException当我试图启动服务。 我写了一个小应用程序,我有一个按钮和2个EditTextes(标题和内容)。当我点击按钮时,我检索EditTextes中的值,并开始一个新的服务来创建一个通知。我的代码分为两部分。这是我的代码。这一个提出申请的主要活动:NullPointerException启动服务
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button button = (Button) findViewById(R.id.serviceButton);
final Context ctx = getApplicationContext();
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
final Intent i = new Intent(ctx, NotificationService.class);
Toast.makeText(ctx, "Clicking ...", Toast.LENGTH_SHORT).show();
EditText title = (EditText) findViewById(R.id.notif_title);
EditText content = (EditText) findViewById(R.id.notif_content);
Bundle bundle = new Bundle();
bundle.putCharSequence("NOTIF_TITLE", title.getText());
bundle.putCharSequence("NOTIF_CONTENT", content.getText());
i.putExtras(bundle);
startService(i);
}
});
}
这其中描述了将推出通知服务:
public class NotificationService extends IntentService {
public NotificationService(String name) {
super(name);
}
@Override
protected void onHandleIntent(Intent intent) {
Context ctx = getApplicationContext();
Toast.makeText(ctx, "NotificationService", Toast.LENGTH_LONG).show();
String ns = Context.NOTIFICATION_SERVICE;
NotificationManager notificationManager = (NotificationManager) getSystemService(ns);
Bundle b = intent.getExtras();
String title = b.getString("NOTIF_TITLE");
String content = b.getString("NOTIF_CONTENT");
Intent i = new Intent(this, NotificationService.class);
PendingIntent pendingIntent = PendingIntent.getActivity(ctx, 0, i,
Intent.FLAG_ACTIVITY_NEW_TASK);
int icon = R.drawable.ic_launcher;
long when = System.currentTimeMillis();
Notification notification = new Notification(icon,
"New notification arrives", when);
notification.setLatestEventInfo(ctx, title, content, pendingIntent);
notificationManager.notify(
NOTIFICATIONS.HELLO_NOTIFICATION.ordinal(), notification);
}
}
当我按一下按钮,我有这样的例外:
FATAL EXCEPTION: main
java.lang.NullPointerException
at android.content.ContextWrapper.startService(ContextWrapper.java:336)
at com.androidprojects.AndroidActivity$1.onClick(AndroidActivity.java:67)
at android.view.View.performClick(View.java:2485)
at android.view.View$PerformClick.run(View.java:9080)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:3683)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
at dalvik.system.NativeStart.main(Native Method)
FATAL EXCEPTION: main
java.lang.NullPointerException
at android.content.ContextWrapper.startService(ContextWrapper.java:336)
at com.androidprojects.AndroidActivity$1.onClick(AndroidActivity.java:62)
at android.view.View.performClick(View.java:2485)
at android.view.View$PerformClick.run(View.java:9080)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:3683)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
at dalvik.system.NativeStart.main(Native Method)
编辑:我对我的代码进行了更正,删除了new NotificationService
但我还是得到了NullPointerException
我认为没有必要为NotificationService notificationService = new NotificationService(“”);只需调用你的startService(intent); – Akram
或 .this.startService(i); ................. –