我正在研究片段活动以在姜饼操作系统上工作。当我尝试在姜饼模拟器上运行应用程序时，应用程序由于ClassNotFound错误而被强制关闭。我在下面提供我的主要片段活动代码
一种和平的帮助将是可观的。
package com.example.android.effectivenavigation;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.ActionBar;
import android.app.FragmentTransaction;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
@SuppressLint("NewApi")
public class MainActivity extends FragmentActivity implements ActionBar.TabListener {
/**
* The {@link android.support.v4.view.PagerAdapter} that will provide fragments for each of the
* three primary sections of the app. We use a {@link android.support.v4.app.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}.
*/
AppSectionsPagerAdapter mAppSectionsPagerAdapter;
/**
* The {@link ViewPager} that will display the three primary sections of the app, one at a
* time.
*/
ViewPager mViewPager;
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
@SuppressLint("NewApi")
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Create the adapter that will return a fragment for each of the three primary sections
// of the app.
mAppSectionsPagerAdapter = new AppSectionsPagerAdapter(getSupportFragmentManager());
// Set up the action bar.
final ActionBar actionBar = getActionBar();
// Specify that the Home/Up button should not be enabled, since there is no hierarchical
// parent.
actionBar.setHomeButtonEnabled(false);
// Specify that we will be displaying tabs in the action bar.
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Set up the ViewPager, attaching the adapter and setting up a listener for when the
// user swipes between sections.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mAppSectionsPagerAdapter);
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
@SuppressLint("NewApi")
@Override
public void onPageSelected(int position) {
// When swiping between different app sections, select the corresponding tab.
// We can also use ActionBar.Tab#select() to do this if we have a reference to the
// Tab.
actionBar.setSelectedNavigationItem(position);
}
});
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mAppSectionsPagerAdapter.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
// listener for when this tab is selected.
actionBar.addTab(
actionBar.newTab()
.setText(mAppSectionsPagerAdapter.getPageTitle(i))
.setTabListener(this));
}
}
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}
@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 onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}
/**
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to one of the primary
* sections of the app.
*/
public static class AppSectionsPagerAdapter extends FragmentPagerAdapter {
public AppSectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int i) {
switch (i) {
case 0:
// The first section of the app is the most interesting -- it offers
// a launchpad into the other demonstrations in this example application.
return new LaunchpadSectionFragment();
default:
// The other sections of the app are dummy placeholders.
Fragment fragment = new DummySectionFragment();
Bundle args = new Bundle();
args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, i + 1);
fragment.setArguments(args);
return fragment;
}
}
@Override
public int getCount() {
return 3;
}
@Override
public CharSequence getPageTitle(int position) {
return "Section " + (position + 1);
}
}
/**
* A fragment that launches other parts of the demo application.
*/
public static class LaunchpadSectionFragment extends Fragment {
ArrayAdapter<String> adapter;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_section_launchpad, container, false);
ListView listView = (ListView)rootView.findViewById(R.id.listview);
String[] values = new String[] {"Akshay Borgave","Pramod Mahake","Vishal Lokhande","Vivek Chaudhari","Rahul Borole","Neha Gadekar"};
adapter = new ArrayAdapter<String>(getActivity(),android.R.layout.simple_list_item_2, android.R.id.text1, values);
listView.setAdapter(adapter);
// Demonstration of a collection-browsing activity.
/*rootView.findViewById(R.id.demo_collection_button)
.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(getActivity(), CollectionDemoActivity.class);
startActivity(intent);
}
});*/
// Demonstration of navigating to external activities.
/* rootView.findViewById(R.id.demo_external_activity)
.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// Create an intent that asks the user to pick a photo, but using
// FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET, ensures that relaunching
// the application from the device home screen does not return
// to the external activity.
Intent externalActivityIntent = new Intent(Intent.ACTION_PICK);
externalActivityIntent.setType("image/*");
externalActivityIntent.addFlags(
Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
startActivity(externalActivityIntent);
}
});*/
return rootView;
}
}
/**
* A dummy fragment representing a section of the app, but that simply displays dummy text.
*/
public static class DummySectionFragment extends Fragment {
public static final String ARG_SECTION_NUMBER = "section_number";
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_section_dummy, container, false);
Bundle args = getArguments();
((TextView) rootView.findViewById(android.R.id.text1)).setText(
getString(R.string.dummy_section_text, args.getInt(ARG_SECTION_NUMBER)));
return rootView;
}
}
}
清单看起来像这样
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.effectivenavigation"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="9"
android:targetSdkVersion="10"/>
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@android:style/Theme.WithActionBar" >
<activity
android:name=".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>
<activity
android:name=".CollectionDemoActivity"
android:label="@string/demo_collection" />
</application>
logcat 是
06-12 16:37:17.099: E/AndroidRuntime(378): FATAL EXCEPTION: main
06-12 16:37:17.099: E/AndroidRuntime(378): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.android.effectivenavigation/com.example.android.effectivenavigation.MainActivity}: java.lang.ClassNotFoundException: com.example.android.effectivenavigation.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.example.android.effectivenavigation-1.apk]
06-12 16:37:17.099: E/AndroidRuntime(378): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1569)
06-12 16:37:17.099: E/AndroidRuntime(378): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
06-12 16:37:17.099: E/AndroidRuntime(378): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
06-12 16:37:17.099: E/AndroidRuntime(378): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
06-12 16:37:17.099: E/AndroidRuntime(378): at android.os.Handler.dispatchMessage(Handler.java:99)
06-12 16:37:17.099: E/AndroidRuntime(378): at android.os.Looper.loop(Looper.java:123)
06-12 16:37:17.099: E/AndroidRuntime(378): at android.app.ActivityThread.main(ActivityThread.java:3683)
06-12 16:37:17.099: E/AndroidRuntime(378): at java.lang.reflect.Method.invokeNative(Native Method)
06-12 16:37:17.099: E/AndroidRuntime(378): at java.lang.reflect.Method.invoke(Method.java:507)
06-12 16:37:17.099: E/AndroidRuntime(378): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
06-12 16:37:17.099: E/AndroidRuntime(378): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
06-12 16:37:17.099: E/AndroidRuntime(378): at dalvik.system.NativeStart.main(Native Method)
06-12 16:37:17.099: E/AndroidRuntime(378): Caused by: java.lang.ClassNotFoundException: com.example.android.effectivenavigation.MainActivity in loader dalvik.system.PathClassLoader[/data/app/com.example.android.effectivenavigation-1.apk]
06-12 16:37:17.099: E/AndroidRuntime(378): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:240)
06-12 16:37:17.099: E/AndroidRuntime(378): at java.lang.ClassLoader.loadClass(ClassLoader.java:551)
06-12 16:37:17.099: E/AndroidRuntime(378): at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
06-12 16:37:17.099: E/AndroidRuntime(378): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
06-12 16:37:17.099: E/AndroidRuntime(378): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1561)
06-12 16:37:17.099: E/AndroidRuntime(378): ... 11 more
片段活动的xml布局文件如下
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
再次提前感谢