Question

我有这个错误我尝试做了很多事情但我找不到解决方案，当我第一次启动应用程序时我获得登录活动并正常工作，我关闭应用程序并重新开始，然后应用程序崩溃，这是堆栈跟踪：

 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.app.Application.getApplicationContext()' on a null object reference
            at com.rrms.jrperera.rapidsentry.poco.AppManager.isConnected(AppManager.java:70)
            at com.rrms.jrperera.rapidsentry.activities.MainActivity.CheckInternetConnection(MainActivity.java:54)
            at com.rrms.jrperera.rapidsentry.activities.MainActivity.HandleSignIn(MainActivity.java:61)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at android.view.View$1.onClick(View.java:4015)
            at android.view.View.performClick(View.java:4780)
            at android.view.View$PerformClick.run(View.java:19866)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5257)

当我从android studio启动应用程序时，这个问题不会发生。当我在某个时刻启动应用程序时，我启动它在后台运行的服务，方法的代码：isConnected和CheckInternetConnection正在一个单独的类中实现，我用它来管理所有应用程序：

public class AppManager {

    public static final String SESSION_DATA = "com.rrms.jrperera.rapidsentry.MiOSSession";
    public static final String SERVICEURL = "https://xxxxxxx.com/RapidSentry/MiOSService.svc";//https://xxxxxxx.com/RapidSentry/MiOSService.svc//http://10.10.20.137/RapidMiOSApi/MiOSService.svc
    private static AppManager manager = null;
    private static Application application;
    private Boolean isServiceRunning = null;

    protected AppManager(Application app) {
        this.setApplication(app);
    }

    public static AppManager getManager(Application app) {
        if (manager == null) {
            manager = new AppManager(app);
        }
        return manager;
    }

    public Application getApplication() {
        return application;
    }

    public void setApplication(Application application) {
        this.application = application;
    }

    public boolean isConnected() {
        boolean connected = true;
        ConnectivityManager connMgr = (ConnectivityManager)
                getApplication().getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
        if (networkInfo != null && networkInfo.isConnected())
            connected = true;
        return connected;
    }
}

当应用程序崩溃时，我再次启动应用程序并再次正常工作。请知道这是怎么回事？这是活动代码：

public class MainActivity extends AppCompatActivity {

protected AppManager manager = null;
protected EditText tbLoginUser = null;
protected EditText tbLoginPassword = null;
protected CheckBox cbLoginSaveCredentials = null;
protected ProgressBar pbLogin = null;
protected Button btSignIn = null;
protected Identity myIdentiy = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    isMyServiceRunning();
    tbLoginUser = (EditText) findViewById(R.id.tb_login_user);
    tbLoginPassword = (EditText) findViewById(R.id.tb_login_password);
    pbLogin = (ProgressBar) findViewById(R.id.loginProgressBar);
    pbLogin.setVisibility(View.INVISIBLE);
    btSignIn = (Button) findViewById(R.id.bt_login_signin);
    cbLoginSaveCredentials = (CheckBox) findViewById(R.id.cb_login_save_credential);
    manager = AppManager.getManager(getApplication());
    if (manager.fileExistance("rapid-sentry-identity.txt")) {
        pbLogin.setVisibility(View.VISIBLE);
        new GetIdentityFile().execute();
    }
}

private boolean CheckInternetConnection() {
    manager = AppManager.getManager(getApplication());
    boolean isConnected = false;
    isConnected = manager.isConnected();
    return isConnected;
}

public void HandleSignIn(View view) {
    pbLogin.setVisibility(View.VISIBLE);
    manager = AppManager.getManager(getApplication());
    if (!CheckInternetConnection()) {
        Toast.makeText(manager.getApplication().getApplicationContext(), R.string.no_internet_connection, Toast.LENGTH_SHORT).show();
    } else {
        String user = tbLoginUser.getText().toString();
        String password = tbLoginPassword.getText().toString();
        new Login().execute(user, password);
    }


}

private void SaveSharePreferences() {
    manager.SaveSharedIdentityObject(myIdentiy);
}

private class Login extends AsyncTask<String, Void, String> {

    @Override
    protected String doInBackground(String... params) {
        String result = null;
        try {
            Identity identity = manager.VerifyLogin(params[0], params[1]);
            myIdentiy = identity;
        } catch (Exception ex) {
            result = null;
        }
        return result;
    }

    @Override
    protected void onPostExecute(String result) {
        pbLogin.setVisibility(View.INVISIBLE);
        if (cbLoginSaveCredentials.isChecked()) {
            new SaveIdentityFile().execute(myIdentiy.getIdentityUser(), myIdentiy.getIdentityPassword());
        }
        if (myIdentiy == null) {
            Animation shake = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.shake);
            tbLoginUser.startAnimation(shake);
            tbLoginPassword.startAnimation(shake);
            Toast.makeText(manager.getApplication().getApplicationContext(), R.string.login_error_login, Toast.LENGTH_SHORT).show();
        } else {
            SaveSharePreferences();
            pbLogin.setVisibility(View.INVISIBLE);
            Intent intentGateway = new Intent(getApplication(), GatewayActivity.class);
            startActivity(intentGateway);
        }
    }
}

private class GetIdentityFile extends AsyncTask<Void, Void, String[]> {

    @Override
    protected String[] doInBackground(Void... params) {
        String[] ident;
        try {
            ident = manager.RetrieveIdentityFromFile();
        } catch (FileNotFoundException ex) {
            ident = null;
        }
        return ident;
    }

    @Override
    protected void onPostExecute(String[] aVoid) {
        if (aVoid != null) {
            new Login().execute(aVoid[0], aVoid[1]);
        }
    }
}

private class SaveIdentityFile extends AsyncTask<String, Void, Void> {

    @Override
    protected Void doInBackground(String... params) {
        try {
            manager.SaveIdentityFile(params[0], params[1]);
        } catch (FileNotFoundException ex) {
            return null;
        }
        return null;
    }
}

private boolean isMyServiceRunning() {
    ActivityManager manager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
    for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
        if ((UpdateShareDataService.class).getName().equals(service.service.getClassName())) {
            Intent intentService = new Intent(getApplicationContext(), UpdateShareDataService.class);
            stopService(intentService);
            return true;
        }
    }
    return false;
}

}

Answer 1

我有这个问题的答案，我在后台池数据中运行服务，但是在这个服务中我使用的是应用程序上下文，当应用程序关闭时，服务重启了好几次。解决方案是调用每个活动的onDestroy（）方法，以确保当您关闭应用程序时，服务也将使用stopService销毁。谢谢大家!!

en

第二次错误启动应用程序

1 个答案: