我是新手。我正在关注http://www.androidhive.info/2015/09/android-material-design-working-with-tabs/
上的滑动标签活动教程我在“return mFragmentList.get（position）;”中输入不兼容类型的错误。在MainActivity.java请帮助。
MainActivity.java
package com.pixalstudio.musicadda;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.widget.Toolbar;
import android.support.v4.app.Fragment;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
}
private void setSupportActionBar(Toolbar toolbar) {
}
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFragment(new OneFragment(), "ONE");
adapter.addFragment(new TwoFragment(), "TWO");
adapter.addFragment(new ThreeFragment(), "THREE");
viewPager.setAdapter(adapter);
}
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<android.app.Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
@Override
public android.support.v4.app.Fragment getItem(int position) {
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
public void addFragment(android.app.Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
}
如果有人需要其他任何帮助，请告诉我。提前谢谢：）
logcat的
03-04 21:38:22.643 2650-2650/com.pixalstudio.musicadda E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.pixalstudio.musicadda, PID: 2650
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.pixalstudio.musicadda/com.pixalstudio.musicadda.MainActivity}: java.lang.ClassCastException: android.support.v7.widget.Toolbar cannot be cast to android.widget.Toolbar
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.ClassCastException: android.support.v7.widget.Toolbar cannot be cast to android.widget.Toolbar
at com.pixalstudio.musicadda.MainActivity.onCreate(MainActivity.java:26)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
03-04 21:38:22.645 1519-1887/system_process W/ActivityManager: Force finishing activity 1 com.pixalstudio.musicadda/.MainA
ctivity
的build.gradle
apply plugin: 'com.android.application'
android {
compileSdkVersion 23
buildToolsVersion "23.0.1"
defaultConfig {
applicationId "com.pixalstudio.musicadda"
minSdkVersion 14
targetSdkVersion 23
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.2.0'
compile 'com.android.support:design:23.2.0'
compile 'com.android.support:support-v4:23.2.0'
}
答案 0 :(得分：1)
变化：
private final List<android.app.Fragment> mFragmentList = new ArrayList<>();
要：
private final List<Fragment> mFragmentList = new ArrayList<>();
您没有像其他地方一样使用支持片段。
与addFragment方法相同：
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
由于您要导入支持库片段Fragment，因此可以仅使用import android.support.v4.app.Fragment;替换这些行。
另请注意，OneFragment，TwoFragment和ThreeFragment必须从支持库片段扩展（如果尚未扩展）。
根据发布的新日志，您还需要从支持库中导入工具栏。
import android.support.v7.widget.Toolbar;
答案 1 :(得分：0)
这就是你的问题所在。您正在使用Android支持库版本7，而教程使用的是Android小部件工具栏。
android.support.v7.widget.Toolbar无法强制转换为android.widget.Toolbar
将布局文件中的工具栏更改为
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay" />
请记住导入此
import android.support.v7.widget.Toolbar;