android studio中的java.lang.NoClassDefFoundError

我在android studio中得到java.lang.NoClassDefFoundError，当我在我的项目中添加一个新类时，该类未被其余代码检测到（它不会因为未按预期工作而产生任何编译时错误）。 在本例中，我添加了一个UtilDateTime类，该类给出java.lang.NoClassDefFoundError。请帮助我，这似乎不是一个编码问题，而是与我使用的库有关的问题（尽管我不确定问题的根源）

日志显示：-

    08-08 17:03:36.832  19979-20179/com.indiacom.salondemo E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #3
    java.lang.RuntimeException: An error occured while executing doInBackground()
            at android.os.AsyncTask$3.done(AsyncTask.java:299)
            at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
            at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
            at java.util.concurrent.FutureTask.run(FutureTask.java:239)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
            at java.lang.Thread.run(Thread.java:838)
     Caused by: java.lang.NoClassDefFoundError: com.indiacom.salondemo.utilities.UtilDateTime
            at com.indiacom.salondemo.asynctask.CalendarApiAsyncTask.getDataFromApi(CalendarApiAsyncTask.java:86)
            at com.indiacom.salondemo.asynctask.CalendarApiAsyncTask.doInBackground(CalendarApiAsyncTask.java:45)
            at com.indiacom.salondemo.asynctask.CalendarApiAsyncTask.doInBackground(CalendarApiAsyncTask.java:22)
            at android.os.AsyncTask$2.call(AsyncTask.java:287)
            at java.util.concurrent.FutureTask.run(FutureTask.java:234)
            at                                
android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
            at java.lang.Thread.run(Thread.java:838)

这是我的代码：-

任命活动类：-

package com.indiacom.salondemo;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.api.client.extensions.android.http.AndroidHttp;
import com.google.api.client.googleapis.extensions.android.gms.auth.GoogleAccountCredential;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.client.util.ExponentialBackOff;


import com.google.api.services.calendar.CalendarScopes;
import com.indiacom.salondemo.asynctask.CalendarApiAsyncTask;
import com.indiacom.salondemo.utilities.UtilDateTime;

import android.accounts.AccountManager;
import android.app.Activity;
import android.app.Dialog;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.Typeface;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.text.TextUtils;
import android.text.method.ScrollingMovementMethod;
import android.util.Log;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class AppointmentActivity extends Activity {
    /**
     * A Google Calendar API service object used to access the API.
     * Note: Do not confuse this class with API library's model classes, which
     * represent specific data structures.
     */
    public com.google.api.services.calendar.Calendar mService;

    GoogleAccountCredential credential;
    private TextView mStatusText;
    private TextView mResultsText;
    final HttpTransport transport = AndroidHttp.newCompatibleTransport();
    final JsonFactory jsonFactory = GsonFactory.getDefaultInstance();

    public static final int REQUEST_ACCOUNT_PICKER = 1000;
   public static final int REQUEST_AUTHORIZATION = 1001;
    static final int REQUEST_GOOGLE_PLAY_SERVICES = 1002;
    private static final String PREF_ACCOUNT_NAME = "accountName";
    private static final String[] SCOPES = { CalendarScopes.CALENDAR_READONLY };

    /**
     * Create the main activity.
     * @param savedInstanceState previously saved instance data.
     */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        LinearLayout activityLayout = new LinearLayout(this);
        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.MATCH_PARENT,
                LinearLayout.LayoutParams.MATCH_PARENT);
        activityLayout.setLayoutParams(lp);
        activityLayout.setOrientation(LinearLayout.VERTICAL);
        activityLayout.setPadding(16, 16, 16, 16);

        ViewGroup.LayoutParams tlp = new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.WRAP_CONTENT);

        mStatusText = new TextView(this);
        mStatusText.setLayoutParams(tlp);
        mStatusText.setTypeface(null, Typeface.BOLD);
        mStatusText.setText("Retrieving data...");
        activityLayout.addView(mStatusText);

        mResultsText = new TextView(this);
        mResultsText.setLayoutParams(tlp);
        mResultsText.setPadding(16, 16, 16, 16);
        mResultsText.setVerticalScrollBarEnabled(true);
        mResultsText.setMovementMethod(new ScrollingMovementMethod());
        activityLayout.addView(mResultsText);

        setContentView(activityLayout);

        // Initialize credentials and service object.
        SharedPreferences settings = getPreferences(Context.MODE_PRIVATE);
        credential = GoogleAccountCredential.usingOAuth2(
                getApplicationContext(), Arrays.asList(SCOPES))
                .setBackOff(new ExponentialBackOff())
                .setSelectedAccountName(settings.getString(PREF_ACCOUNT_NAME, null));

        mService = new com.google.api.services.calendar.Calendar.Builder(
                transport, jsonFactory, credential)
                .setApplicationName("Google Calendar API Android Quickstart")
                .build();
    }

    /**
     * Called whenever this activity is pushed to the foreground, such as after
     * a call to onCreate().
     */
    @Override
    protected void onResume() {
        super.onResume();
        if (isGooglePlayServicesAvailable()) {
            refreshResults();
        } else {
            mStatusText.setText("Google Play Services required: " +
                    "after installing, close and relaunch this app.");
        }
    }

    /**
     * Called when an activity launched here (specifically, AccountPicker
     * and authorization) exits, giving you the requestCode you started it with,
     * the resultCode it returned, and any additional data from it.
     * @param requestCode code indicating which activity result is incoming.
     * @param resultCode code indicating the result of the incoming
     *     activity result.
     * @param data Intent (containing result data) returned by incoming
     *     activity result.
     */
    @Override
    protected void onActivityResult(
            int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch(requestCode) {
            case REQUEST_GOOGLE_PLAY_SERVICES:
                if (resultCode != RESULT_OK) {
                    isGooglePlayServicesAvailable();
                }
                break;
            case REQUEST_ACCOUNT_PICKER:
                if (resultCode == RESULT_OK && data != null &&
                        data.getExtras() != null) {
                    String accountName =
                            data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
                    if (accountName != null) {
                        credential.setSelectedAccountName(accountName);
                        SharedPreferences settings =
                                getPreferences(Context.MODE_PRIVATE);
                        SharedPreferences.Editor editor = settings.edit();
                        editor.putString(PREF_ACCOUNT_NAME, accountName);
                        editor.commit();
                    }
                } else if (resultCode == RESULT_CANCELED) {
                    mStatusText.setText("Account unspecified.");
                }
                break;
            case REQUEST_AUTHORIZATION:
                if (resultCode != RESULT_OK) {
                    chooseAccount();
                }
                break;
        }

        super.onActivityResult(requestCode, resultCode, data);
    }

    /**
     * Attempt to get a set of data from the Google Calendar API to display. If the
     * email address isn't known yet, then call chooseAccount() method so the
     * user can pick an account.
     */
    private void refreshResults() {
        if (credential.getSelectedAccountName() == null) {
            chooseAccount();
        } else {
            if (isDeviceOnline()) {
               new CalendarApiAsyncTask(this).execute();
            } else {
                mStatusText.setText("No network connection available.");
            }
        }
    }

    /**
     * Clear any existing Google Calendar API data from the TextView and update
     * the header message; called from background threads and async tasks
     * that need to update the UI (in the UI thread).
     */
    public void clearResultsText() {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mStatusText.setText("Retrieving data…");
                mResultsText.setText("");
            }
        });
    }

    /**
     * Fill the data TextView with the given List of Strings; called from
     * background threads and async tasks that need to update the UI (in the
     * UI thread).
     * @param dataStrings a List of Strings to populate the main TextView with.
     */
    public void updateResultsText(final ArrayList<UtilDateTime> dataStrings) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                if (dataStrings == null) {
                    mStatusText.setText("Error retrieving data!");
                } else if (dataStrings.size() == 0) {
                    mStatusText.setText("No data found.");
                }else{
                    mStatusText.setText("Data retrieved using" +
                            " the Google Calendar API:");

                    String sss=dataStrings.get(0).getmDate();

                    Log.d("Sample String:","String sss="+sss);

                    mResultsText.setText(sss);
                }
            }
        });
    }

    /**
     * Show a status message in the list header TextView; called from background
     * threads and async tasks that need to update the UI (in the UI thread).
     * @param message a String to display in the UI header TextView.
     */
    public void updateStatus(final String message) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                mStatusText.setText(message);
            }
        });
    }

    /**
     * Starts an activity in Google Play Services so the user can pick an
     * account.
     */
    private void chooseAccount() {
        startActivityForResult(
                credential.newChooseAccountIntent(), REQUEST_ACCOUNT_PICKER);
    }

    /**
     * Checks whether the device currently has a network connection.
     * @return true if the device has a network connection, false otherwise.
     */
    private boolean isDeviceOnline() {
        ConnectivityManager connMgr =
                (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
        return (networkInfo != null && networkInfo.isConnected());
    }

    /**
     * Check that Google Play services APK is installed and up to date. Will
     * launch an error dialog for the user to update Google Play Services if
     * possible.
     * @return true if Google Play Services is available and up to
     *     date on this device; false otherwise.
     */
    private boolean isGooglePlayServicesAvailable() {
        final int connectionStatusCode =
                GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
        if (GooglePlayServicesUtil.isUserRecoverableError(connectionStatusCode)) {
            showGooglePlayServicesAvailabilityErrorDialog(connectionStatusCode);
            return false;
        } else if (connectionStatusCode != ConnectionResult.SUCCESS ) {
            return false;
        }
        return true;
    }

    /**
     * Display an error dialog showing that Google Play Services is missing
     * or out of date.
     * @param connectionStatusCode code describing the presence (or lack of)
     *     Google Play Services on this device.
     */
   public void showGooglePlayServicesAvailabilityErrorDialog(
            final int connectionStatusCode) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Dialog dialog = GooglePlayServicesUtil.getErrorDialog(
                        connectionStatusCode,
                        AppointmentActivity.this,
                        REQUEST_GOOGLE_PLAY_SERVICES);
                dialog.show();
            }
        });
    }

}

package com.indiacom.salondemo.asynctask;
import android.os.AsyncTask;
import android.util.Log;

import com.google.api.client.googleapis.extensions.android.gms.auth.GooglePlayServicesAvailabilityIOException;
import com.google.api.client.googleapis.extensions.android.gms.auth.UserRecoverableAuthIOException;
import com.google.api.client.util.DateTime;

import com.google.api.services.calendar.model.*;
import com.indiacom.salondemo.AppointmentActivity;
import com.indiacom.salondemo.AppointmentActivity;
import com.indiacom.salondemo.utilities.UtilDateTime;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * An asynchronous task that handles the Google Calendar API call.
 * Placing the API calls in their own task ensures the UI stays responsive.
 */
public class CalendarApiAsyncTask extends AsyncTask<Void, Void, Void> {
    private AppointmentActivity mActivity;

    ArrayList<UtilDateTime> mArrList;

    /**
     * Constructor.
     *
     * @param activity MainActivity that spawned this task.
     */
    public CalendarApiAsyncTask(AppointmentActivity activity) {
        this.mActivity = activity;
    }

    /**
     * Background task to call Google Calendar API.
     *
     * @param params no parameters needed for this task.
     */
    @Override
    protected Void doInBackground(Void... params) {
        try {
            mActivity.clearResultsText();
            mActivity.updateResultsText(getDataFromApi());

        } catch (final GooglePlayServicesAvailabilityIOException availabilityException) {
            mActivity.showGooglePlayServicesAvailabilityErrorDialog(
                    availabilityException.getConnectionStatusCode());

        } catch (UserRecoverableAuthIOException userRecoverableException) {
            mActivity.startActivityForResult(
                    userRecoverableException.getIntent(),
                    AppointmentActivity.REQUEST_AUTHORIZATION);

        } catch (Exception e) {
            mActivity.updateStatus("The following error occurred:\n" +
                    e.getMessage());
        }
        return null;
    }

    /**
     * Fetch a list of the next 10 events from the primary calendar.
     *
     * @return List of Strings describing returned events.
     * @throws IOException
     */
    private ArrayList<UtilDateTime> getDataFromApi() throws IOException {
        // List the next 10 events from the primary calendar.
        DateTime now = new DateTime(System.currentTimeMillis());
        List<String> eventStrings = new ArrayList<String>();
        Events events = mActivity.mService.events().list("primary")
                .setMaxResults(10)
                .setTimeMin(now)
                .setOrderBy("startTime")
                .setSingleEvents(true)
                .execute();
        List<Event> items = events.getItems();

        mArrList= new ArrayList<UtilDateTime>();

        for(int i=0;i<5;i++)
        {

           UtilDateTime  objectForDateTime=new UtilDateTime();
            objectForDateTime.setmDate("12-7-2015");
            objectForDateTime.setmTime("12.00");
            mArrList.add(objectForDateTime);

        }


       Log.e("arraylist::","list:"+mArrList.get(0).getmDate());
//
//        for (Event event : items) {
//            DateTime start = event.getStart().getDateTime();
//            if (start == null) {
//                // All-day events don't have start times, so just use
//                // the start date.
//                start = event.getStart().getDate();
//            }
//            eventStrings.add(
//                    String.format("%s (%s)", event.getSummary(), start));
//        }
        return mArrList;
    }

}

    package com.indiacom.salondemo.utilities;

/**
 * Created by cloud1 on 7/8/15.
 */
public class UtilDateTime {

    String mDate, mTime;

    public UtilDateTime()
    {

    }

    public UtilDateTime(String mDate, String mTime) {
        this.mDate = mDate;
        this.mTime = mTime;
    }

    public String getmDate() {
        return mDate;
    }

    public void setmDate(String mDate) {
        this.mDate = mDate;
    }

    public String getmTime() {
        return mTime;
    }

    public void setmTime(String mTime) {
        this.mTime = mTime;
    }
}