我尝试使用v7支持库中的PreferenceFragment来设置我的应用。当我尝试在android 4.2.2中运行它时，它总是返回以下异常：
E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{fr.mobiho.navapp/fr.mobiho.navapp.settings.activity.PrefsActivity}: android.app.Fragment$InstantiationException: Unable to instantiate fragment android.support.v14.preference.PreferenceFragment: make sure class name exists, is public, and has an empty constructor that is public
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.app.Fragment$InstantiationException: Unable to instantiate fragment android.support.v14.preference.PreferenceFragment: make sure class name exists, is public, and has an empty constructor that is public
at android.app.Fragment.instantiate(Fragment.java:596)
at android.preference.PreferenceActivity.switchToHeaderInner(PreferenceActivity.java:1138)
at android.preference.PreferenceActivity.switchToHeader(PreferenceActivity.java:1154)
at android.preference.PreferenceActivity.onCreate(PreferenceActivity.java:560)
at fr.mobiho.navapp.activity.AppCompatPreferenceActivity.onCreate(AppCompatPreferenceActivity.java:35)
at fr.mobiho.navapp.settings.activity.ThemableSettingsActivity.onCreate(ThemableSettingsActivity.java:39)
at fr.mobiho.navapp.settings.activity.PrefsActivity.onCreate(PrefsActivity.java:53)
at android.app.Activity.performCreate(Activity.java:5104)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.InstantiationException: can't instantiate class android.support.v14.preference.PreferenceFragment
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1319)
at android.app.Fragment.instantiate(Fragment.java:585)
at android.preference.PreferenceActivity.switchToHeaderInner(PreferenceActivity.java:1138)
at android.preference.PreferenceActivity.switchToHeader(PreferenceActivity.java:1154)
at android.preference.PreferenceActivity.onCreate(PreferenceActivity.java:560)
at fr.mobiho.navapp.activity.AppCompatPreferenceActivity.onCreate(AppCompatPreferenceActivity.java:35)
at fr.mobiho.navapp.settings.activity.ThemableSettingsActivity.onCreate(ThemableSettingsActivity.java:39)
at fr.mobiho.navapp.settings.activity.PrefsActivity.onCreate(PrefsActivity.java:53)
at android.app.Activity.performCreate(Activity.java:5104)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)
但在更高版本中，它的工作正常，如5.0,5.1,6.0。
这是AppCompatPreferenceActivity类
public abstract class AppCompatPreferenceActivity extends PreferenceActivity {
private AppCompatDelegate mDelegate;
@Override
protected void onCreate(Bundle savedInstanceState) {
overridePendingTransition(R.anim.slide_in_from_right, R.anim.fade_out_scale);
getDelegate().installViewFactory();
getDelegate().onCreate(savedInstanceState);
super.onCreate(savedInstanceState);
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
getDelegate().onPostCreate(savedInstanceState);
}
protected final ActionBar getSupportActionBar() {
return getDelegate().getSupportActionBar();
}
protected final void setSupportActionBar(@Nullable Toolbar toolbar) {
getDelegate().setSupportActionBar(toolbar);
}
@NonNull
@Override
public MenuInflater getMenuInflater() {
return getDelegate().getMenuInflater();
}
@Override
public void setContentView(@LayoutRes int layoutResID) {
getDelegate().setContentView(layoutResID);
}
@Override
public void setContentView(View view) {
getDelegate().setContentView(view);
}
@Override
public void setContentView(View view, ViewGroup.LayoutParams params) {
getDelegate().setContentView(view, params);
}
@Override
public void addContentView(View view, ViewGroup.LayoutParams params) {
getDelegate().addContentView(view, params);
}
@Override
protected void onPostResume() {
super.onPostResume();
getDelegate().onPostResume();
}
@Override
protected void onTitleChanged(CharSequence title, int color) {
super.onTitleChanged(title, color);
getDelegate().setTitle(title);
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
getDelegate().onConfigurationChanged(newConfig);
}
@Override
protected void onPause() {
super.onPause();
if (isFinishing()) {
overridePendingTransition(R.anim.fade_in_scale, R.anim.slide_out_to_right);
}
}
@Override
protected void onStop() {
super.onStop();
getDelegate().onStop();
}
@Override
protected void onDestroy() {
super.onDestroy();
getDelegate().onDestroy();
}
public void invalidateOptionsMenu() {
getDelegate().invalidateOptionsMenu();
}
private AppCompatDelegate getDelegate() {
if (mDelegate == null) {
mDelegate = AppCompatDelegate.create(this, null);
}
return mDelegate;
}
}
这是MyCustomPreferenceFragment
public class MyCustomPreferenceFragment extends PreferenceFragment {
@Inject
PreferenceManager mPreferenceManager;
public MyCustomPreferenceFragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
}
}
答案 0 :(得分：2)
您必须删除abstract关键字，因为无法实例化抽象类，因此请使用
public /*abstract*/ class AppCompatPreferenceActivity extends PreferenceActivity {