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私はサービスに接続していて、その中のオブジェクトにアクセスするAndroidアプリケーションを開発中です。 1つのクラスに対して同じメカニズムが働いていて、NPEで他のクラスでは失敗しています。私はなぜ、何がうまくいかないのか分からない。どんな助けもいいだろう。Android：サービスから取得したオブジェクトもバインドサービス後もnullです
エラーログ：
java.lang.RuntimeException: Unable to start activity ComponentInfo
{mycompany.notes/mycompany.notes.Activity.ChatMessagesActivity}: java.lang.NullPointerException: Attempt to read from field 'org.cometd.client.BayeuxClient mycompany.notes.Activity.ConsoleChatClient.client' on a null object reference
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.NullPointerException: Attempt to read from field 'org.cometd.client.BayeuxClient mycompany.notes.Activity.ConsoleChatClient.client' on a null object reference
at mycompany.notes.Activity.ChatMessagesActivity.onCreate(ChatMessagesActivity.java:177)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
サービスコード：
public class ConsoleChatClient extends Service {
private final IBinder mBinder = new LocalBinder();
BayeuxClient client;
HttpClient httpClient = StaticRestTemplate.getHttpClient();
String defaultURL = StaticRestTemplate.baseURL + "/cometd";
public class LocalBinder extends Binder {
ConsoleChatClient getService() {
// Return this instance of LocalService so clients can call public methods
return ConsoleChatClient.this;
}
}
private void connectionEstablished() {
System.err.printf("system: Connection to Server Opened%n");
}
private void connectionClosed() {
System.err.printf("system: Connection to Server Closed%n");
}
private void connectionBroken() {
System.err.printf("system: Connection to Server Broken%n");
}
@Override
public void onCreate() {
super.onCreate();
performConnection();
}
@Override
public IBinder onBind(Intent intent) {
performConnection();
return mBinder;
}
private void performConnection() {
try {
httpClient.start();
ClientTransport clientTransport = new LongPollingTransport(null, httpClient);
bayeuxClient = new BayeuxClient(defaultURL, clientTransport);
// Below for use with Spring-Security post-login.
bayeuxClient.putCookie(new HttpCookie("JSESSIONID", StaticRestTemplate.getJsessionid()));
bayeuxClient.getChannel(Channel.META_HANDSHAKE).addListener(new InitializerListener());
bayeuxClient.getChannel(Channel.META_CONNECT).addListener(new ConnectionListener());
bayeuxClient.handshake();
StaticRestTemplate.setClient(bayeuxClient);
StaticRestTemplate.setHttpClient(httpClient);
boolean success = bayeuxClient.waitFor(2000, BayeuxClient.State.CONNECTED);
if (!success) {
System.err.printf("Could not handshake with server at %s%n", defaultURL);
}else {
System.err.printf("Handhskare complete");
}
} catch (Exception ignored) {}
}
}
ChatMessagesActivity.java：
public class ChatMessagesActivity extends ApplicationDrawerLoader {
HttpClient httpClient;
ConsoleChatClient consoleChatClient;
boolean mBound = false;
private ChatListener chatListener = new ChatListener();
@Override
protected void onStart() {
super.onStart();
Intent intent = new Intent(this, ConsoleChatClient.class);
bindService(intent, mConnection, Context.BIND_IMPORTANT);
}
private ServiceConnection mConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName className,
IBinder service) {
ConsoleChatClient.LocalBinder binder = (ConsoleChatClient.LocalBinder) service;
consoleChatClient = binder.getService();
mBound = true;
}
@Override
public void onServiceDisconnected(ComponentName arg0) {
mBound = false;
}
};
@Override
protected void onStop() {
super.onStop();
// Unbind from the service
if (mBound) {
unbindService(mConnection);
mBound = false;
if (conversationId != 0) {
consoleChatClient.client.getChannel("/person/" + conversationId).unsubscribe();
}
if (groupAccountId != 0) {
consoleChatClient.client.getChannel("/chat/" + conversationId).unsubscribe();
}
}
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat_messages);
try {
Intent intent = new Intent(this, ConsoleChatClient.class);
startService(intent);
httpClient = consoleChatClient.httpClient;
} catch (Exception ignored) {
}
// Below code crashes at consoleChatClient.client
if (conversationId != 0) {
consoleChatClient.client.getChannel("/person/" + conversationId).subscribe(chatListener);
}
if (groupAccountId != 0) {
consoleChatClient.client.getChannel("/chat/" + conversationId).subscribe(chatListener);
}
}
だから、私はそれが一つのクラスに動作することを間違って何をやっている、と他にはない。助けてください。ありがとうございました。
？ –
'httpClient = consoleChatClient.httpClient;'ここで 'consoleChatClient'はnullです – pskink
@pskink：実際には、httpClientはnullではなく、BayeuxClientはnullです。それが私を混乱させている、私はそれを確認した。 –