java - 通用类未找到异常

Question

由于未找到类异常，我收到无法实例化 fragment 错误。以前这段代码工作得很好，我不知道发生了什么变化，我已经尝试解决这个问题几个小时了。

代码

AddEvents 类

package com.whatshappening;
// A bunch of imports

public class AddEvents extends Fragment implements
        GooglePlayServicesClient.ConnectionCallbacks,
        GooglePlayServicesClient.OnConnectionFailedListener, AsyncResponse, locationChangeListner {
    // Class Variables
    private ProgressDialog pd;
    private LocationClient mLocationClient;
    private FragmentActivity myContext;
    private String resultString;

    public String LatLng = null;
    public EditText locationAddress = null;
    public Double Lat = null;
    public Double Lng = null;
    public Double lat = null;
    public Double lng = null;

    // Constructor is empty and public
    public AddEvents(){

    }

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.add_events, container, false);
        locationAddress = (EditText) rootView.findViewById(R.id.tLocation);
        mLocationClient = new LocationClient(getActivity(), this, this);
        rootView.findViewById(R.id.locButton).setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        pd = ProgressDialog.show(getActivity(), "",
                                "Finding you!!!", false);
                        getAddress(v);

                    }

                });

        rootView.findViewById(R.id.shButton).setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {                       
                        if ((Lat != null) && (Lng != null)) {
                            Toast.makeText(getActivity(),
                                    LatLng, Toast.LENGTH_SHORT).show();
                            locationChange(Lat,Lng);
                        } else {
                            Toast.makeText(getActivity(),
                                    "No location was found", Toast.LENGTH_SHORT).show();
                        }
                    }
        }); 

        return rootView;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
    }

 // Class is much Larger but I don't think that's the issue.
 }

主要 Activity

package com.whatshappening;
//Bunch of imports 

public class MainActivity extends ActionBarActivity implements
        ActionBar.TabListener {

    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a {@link FragmentPagerAdapter}
     * derivative, which will keep every loaded fragment in memory. If this
     * becomes too memory intensive, it may be best to switch to a
     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
     */
    SectionsPagerAdapter mSectionsPagerAdapter;

    /**
     * The {@link ViewPager} that will host the section contents.
     */
    ViewPager mViewPager;

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

        // Set up the action bar.
        final ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        // Set up date in Action Bar
        String dateString = (String) DateFormat.format("MM-dd-yyyy",
                new java.util.Date());
        actionBar.setSubtitle(dateString);

        // Create the adapter that will return a fragment for each of the three
        // primary sections of the activity.
        mSectionsPagerAdapter = new SectionsPagerAdapter(
                getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mSectionsPagerAdapter);

        // When swiping between different sections, select the corresponding
        // tab. We can also use ActionBar.Tab#select() to do this if we have
        // a reference to the Tab.
        mViewPager
                .setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
                    @Override
                    public void onPageSelected(int position) {
                        actionBar.setSelectedNavigationItem(position);
                    }
                });

        // For each of the sections in the app, add a tab to the action bar.
        for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
            // Create a tab with text corresponding to the page title defined by
            // the adapter. Also specify this Activity object, which implements
            // the TabListener interface, as the callback (listener) for when
            // this tab is selected.
            actionBar.addTab(actionBar.newTab()
                    .setText(mSectionsPagerAdapter.getPageTitle(i))
                    .setTabListener(this));
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab,
            FragmentTransaction fragmentTransaction) {
        // When the given tab is selected, switch to the corresponding page in
        // the ViewPager.
        mViewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab,
            FragmentTransaction fragmentTransaction) {
    }

    @Override
    public void onTabReselected(ActionBar.Tab tab,
            FragmentTransaction fragmentTransaction) {
    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public android.support.v4.app.Fragment getItem(int position) {
            switch (position) {
            case (0):
                return new AddEvents();
            case (1):
                return new EventMap();
            }
            return null;

        }

        @Override
        public int getCount() {
            // Show 2 total pages.
            return 2;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            Locale l = Locale.getDefault();
            switch (position) {
            case 0:
                return getString(R.string.title_section1).toUpperCase(l);
            case 1:
                return getString(R.string.title_section2).toUpperCase(l);
            }
            return null;
        }
    }
}

Android list 文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.whatshappening"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="19" />

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
    <!--
     The following two permissions are not required to use
     Google Maps Android API v2, but are recommended.
    -->
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/Theme.AppCompat.Light" >
        <meta-data
            android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />
        <meta-data
            android:name="com.google.android.maps.v2.API_KEY"
            android:value="AIzaSyCO5Wb1Ow2W3Wq0mB64OFIPwTvGLbCRS9k" />

        <activity
            android:name="com.whatshappening.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

日志猫

07-19 19:46:15.880: E/AndroidRuntime(29720): Caused by: android.app.Fragment$InstantiationException: Unable to instantiate fragment com.example.fragment.AddEvents: make sure class name exists, is public, and has an empty constructor that is public
07-19 19:46:15.880: E/AndroidRuntime(29720):    at android.app.Fragment.instantiate(Fragment.java:597)
07-19 19:46:15.880: E/AndroidRuntime(29720):    at android.app.Fragment.instantiate(Fragment.java:561)
07-19 19:46:15.880: E/AndroidRuntime(29720):    at android.app.Activity.onCreateView(Activity.java:4964)
07-19 19:46:15.880: E/AndroidRuntime(29720):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:695)
07-19 19:46:15.880: E/AndroidRuntime(29720):    ... 24 more
07-19 19:46:15.880: E/AndroidRuntime(29720): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.fragment.AddEvents" on path: DexPathList[[zip file "/data/app/com.whatshappening-13.apk"],nativeLibraryDirectories=[/data/app-lib/com.whatshappening-13, /vendor/lib, /system/lib]]
07-19 19:46:15.880: E/AndroidRuntime(29720):    at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:67)
07-19 19:46:15.880: E/AndroidRuntime(29720):    at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
07-19 19:46:15.880: E/AndroidRuntime(29720):    at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
07-19 19:46:15.880: E/AndroidRuntime(29720):    at android.app.Fragment.instantiate(Fragment.java:583)
07-19 19:46:15.880: E/AndroidRuntime(29720):    ... 27 more

add_events.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/beaver"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/tVName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="20dp"
        android:layout_marginTop="30dp"
        android:text="Event Name:"
        android:textColor="@android:color/white"
        android:textSize="22sp" />

    <Button
        android:id="@+id/locButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/tLocation"
        android:layout_alignBottom="@+id/tLocation"
        android:layout_alignParentRight="true"
        android:text="Get Location"
        android:textColor="#ffffff" />

    <EditText
        android:id="@+id/tLocation"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tVLocation"
        android:layout_marginTop="25dp"
        android:layout_toLeftOf="@+id/locButton"
        android:ems="10"
        android:textColor="@android:color/white" />

    <EditText
        android:id="@+id/tTime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/tVTime"
        android:layout_below="@+id/tVTime"
        android:layout_marginTop="22dp"
        android:ems="10"
        android:inputType="textMultiLine|date"
        android:textColor="@android:color/white" />

    <TextView
        android:id="@+id/tVDescription"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/tDescription"
        android:layout_alignLeft="@+id/tTime"
        android:layout_marginBottom="18dp"
        android:text="Description:"
        android:textColor="@android:color/white"
        android:textSize="22sp" />

    <EditText
        android:id="@+id/tNames"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/tVLocation"
        android:layout_below="@+id/tVName"
        android:layout_marginTop="10dp"
        android:ems="10"
        android:textColor="@android:color/white" />

    <EditText
        android:id="@+id/tDescription"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/shButton"
        android:layout_alignLeft="@+id/tVDescription"
        android:layout_marginBottom="7dp"
        android:ems="10"
        android:inputType="textMultiLine"
        android:textColor="@android:color/white" />

    <TextView
        android:id="@+id/tVTime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/tVLocation"
        android:layout_below="@+id/locButton"
        android:layout_marginTop="16dp"
        android:text="Time:"
        android:textColor="@android:color/white"
        android:textSize="22sp" />

    <TextView
        android:id="@+id/tVLocation"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/tVName"
        android:layout_below="@+id/tNames"
        android:layout_marginTop="15dp"
        android:text="Location:"
        android:textColor="@android:color/white"
        android:textSize="22sp" />

    <Button
        android:id="@+id/shButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="31dp"
        android:layout_toRightOf="@+id/tDescription"
        android:text="Share"
        android:textColor="#ffffff" />

</RelativeLayout>

我觉得这个错误一定是非常基本的错误。但我没有对应用程序的先前“工作”版本进行任何更改。

Answer 1

Didn't find class "com.example.fragment.AddEvents"

您的 AddEvents 包名称是

package com.whatshappening;

不是

com.example.fragment

看起来布局中的某个位置有 fragment ，但包名称与 fragment 中的包名称不匹配