我的应用程序一直崩溃

Question

我正在使用android studio和名为myCBR的外部库。我正在尝试加载放在我的资源文件夹中的文件。我有一个名为“MainActivity”和“CBRHandler”的主要活动。我可以运行应用程序但是当我尝试通过切换按钮加载项目时，我的应用程序崩溃了。你知道可能导致它的原因吗？

public class MainActivity extends Activity {

Boolean InternetAvailable = false;
Button checkInternet;
DetectConnection detect_connection;
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10L;
private static final long MIN_TIME_PASSED_FOR_UPDATES = 10000L;
private static final String PRJ_FILENAME = "financeDemo.prj";
private static final String PROJECTNAME = "financeDemo";
final String TAG = "[HUB]";
protected CBRHandler cbrHandler = null;
private AsyncTask<String, Integer, String> cbrTask;
protected HashMap<String, String> currentLocales;
protected Location currentLocation;
protected ProgressDialog dialog;
protected LocationManager locManager;
protected Button locationButton;
protected String locationlatitude;
protected String locationlongitude;
protected TextView myCBRtext;
protected ToggleButton myCBRtoggleButton;
protected Button networkButton;
protected TextView networkText;
protected Button socialProfileButton;
protected TextView socialText;
protected Button startQueryButton;
protected Button userDetailsButton;


@Override
protected void onCreate(Bundle paramBundle) {
    super.onCreate(paramBundle);
    setContentView(R.layout.activity_main);

    //Setting up button for "My Librarian" section
    Button MyLibrarian = (Button) findViewById(R.id.btnMyLibrarian);
    MyLibrarian.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            startActivity(new Intent(MainActivity.this, MyLibrarianActivity.class));
        }
    });

    //Setting up button for "Around Me" section
    Button AroundMe = (Button) findViewById(R.id.btnAroundMe);
    AroundMe.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            startActivity(new Intent(MainActivity.this, AroundMeActivity.class));
        }
    });

    //Setting up button for "Find your way" section
    Button FindYourWay = (Button) findViewById(R.id.btnFindYourWay);
    FindYourWay.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            startActivity(new Intent(MainActivity.this, FindYourWayActivity.class));
        }
    });

    //Setting up button for "Author" section
    Button Author = (Button) findViewById(R.id.btnAuthor);
    Author.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            startActivity(new Intent(MainActivity.this, AuthorActivity.class));
        }
    });

    //Setting up "Check for network connectivity button"
    checkInternet = (Button) findViewById(R.id.btnNetworkConnectivity);
    detect_connection = new DetectConnection(getApplicationContext());
    checkInternet.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            InternetAvailable = detect_connection.InternetConnecting();
            if (InternetAvailable) {
                showAlertDialog(MainActivity.this, "Network Connection",
                        "Network connection is available", true);
            } else {
                showAlertDialog(MainActivity.this, "No Network Connection",
                        "Network connection is not available", false);
            }
        }
    });
    {


        this.myCBRtoggleButton = ((ToggleButton) findViewById(R.id.myCBRtoggleButton));
        this.myCBRtoggleButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View paramAnonymousView) {
                if (MainActivity.this.myCBRtoggleButton.isChecked()) {
                    Toast.makeText(MainActivity.this, "Starting a myCBR task", Toast.LENGTH_SHORT).show();
                    MainActivity.this.cbrTask = new MainActivity.OpenMyCBRProjectTask(MainActivity.this).execute(new String[0]);
                    return;
                }
                Toast.makeText(MainActivity.this, "Resetting", Toast.LENGTH_SHORT).show();
                MainActivity.this.cbrTask.cancel(true);
                MainActivity.this.startQueryButton.setEnabled(false);
                CBRHandler.resetInstance();
            }
        });
        this.startQueryButton = ((Button) findViewById(R.id.startQueryButton));
        this.startQueryButton.setEnabled(false);
        this.startQueryButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View paramAnonymousView) {
                Intent localIntent = new Intent(MainActivity.this, MyLibrarianActivity.class);
                MainActivity.this.startActivity(localIntent);
            }
        });


        FileIO.copyAssetFile(this, getResources(), "libraryDemo.prj");
        return;
    }
}


class OpenMyCBRProjectTask extends AsyncTask<String, Integer, String> {
    OpenMyCBRProjectTask() {
    }

    public OpenMyCBRProjectTask(MainActivity mainActivity) {

    }

    protected String doInBackground(String[] paramArrayOfString) {
        MainActivity.this.cbrHandler = CBRHandler.getInstance();
        try {
            MainActivity.this.cbrHandler.createProjectFromPRJ("libraryDemo", "libraryDemo.prj", "data/data/" + MainActivity.this.getPackageName() + "/files/");
            return "Opening project 'libraryDemo'";
        } catch (Exception localException) {
            Log.e("[HUB]", "Exception caught while trying to call createProjectFromPRJ");
            Log.e("[HUB]", localException.toString());
        }
        return "Failed to open project";
    }

    protected void onPostExecute(String paramString) {
        MainActivity.this.myCBRtext.setText("Project: 'libraryDemo'");
        MainActivity.this.startQueryButton.setEnabled(true);
    }

    protected void onProgressUpdate(Integer[] paramArrayOfInteger) {
        super.onProgressUpdate(paramArrayOfInteger);
    }
}

public void showAlertDialog(Context context, String t, String m, Boolean status) {
    AlertDialog message = new AlertDialog.Builder(context).create();
    message.setTitle(t);
    message.setMessage(m);
    message.setButton("OK", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
        }
    });
    message.show();
}

}

我的CBRHandler活动

public class CBRHandler

{

private static CBRHandler singletonInstance;
private final String TAG = "[CBR]";
private Concept concept = null;
private String conceptName = "Resource";
private DefaultCaseBase ResourcesCB;
private String multiplevalueseparator = ",";
private String prjFileName = "";
private Project project = null;
private LinkedHashMap<String, String> queryAttributes = new LinkedHashMap();


public static CBRHandler getInstance()
{
    if (singletonInstance == null)
        singletonInstance = new CBRHandler();
    return singletonInstance;
}

public static void resetInstance()
{
    singletonInstance = null;
}


public void addQueryAttribute(String paramString1, String paramString2)
{
    if (this.queryAttributes.containsKey(paramString1))
        this.queryAttributes.remove(paramString1);
    this.queryAttributes.put(paramString1, paramString2);
}

public void createProjectFromPRJ(String paramString1, String paramString2, String paramString3)
{
    try
    {
        Log.i("[CBR]", "Assigning project: " + paramString3 + paramString2);
        this.project = new Project(paramString3 + paramString2);
        Log.i("[CBR]", "Assigning concept: " + this.conceptName);
        this.concept = this.project.getConceptByID(this.conceptName);
        return;
    }
    catch (Exception localException)
    {
        Log.e("[CBR]", "Failed to create project from .prj");
        Log.e("[CBR]", localException.toString());
    }
}

public boolean hasProject()
{
    return this.project != null;
}

}

我得到的例外是：

 1162-1162/dyankov.mylibraryrecommender E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
        at dyankov.mylibraryrecommender.MainActivities.MainActivity$OpenMyCBRProjectTask.onPostExecute(MainActivity.java:245)
        at dyankov.mylibraryrecommender.MainActivities.MainActivity$OpenMyCBRProjectTask.onPostExecute(MainActivity.java:217)    

Answer 1

在AsyncTask的onPostExecute方法中，您可以执行以下操作：

protected void onPostExecute(String paramString) {
        MainActivity.this.myCBRtext.setText("Project: 'libraryDemo'");
        MainActivity.this.startQueryButton.setEnabled(true);
}

您永远不会正确初始化myCBRtext。您可以在onCreate中执行此操作：

@Override
protected void onCreate(Bundle paramBundle) {
    super.onCreate(paramBundle);
    setContentView(R.layout.activity_main);
    // Add the following
    this.myCBRtext = (TextView) findViewById(R.id.my_cbr_text);
    ....
}