Java 清除内存后强制关闭并恢复应用程序

当我测试我的应用程序时，在关闭应用程序并清理内存（在我的情况下是CleanMaster应用程序）然后再次打开它之后，它会强制关闭。我试图寻找原因，但找不到解决办法

如果不清除内存，它就可以正常工作。我想知道在这些事件之后是否需要保存和恢复任何东西。我对安卓系统相当陌生

这是日志

06-29 11:59:19.479  22283-22283/com.thaifasttel D/WebView﹕ onTrimMemory: 20
06-29 11:59:33.985  22524-22524/com.thaifasttel D/jdwp﹕ sendBufferedRequest : len=0x39
06-29 11:59:33.993  22524-22524/com.thaifasttel W/asset﹕ AssetManager-->addDefaultAssets CIP path not exsit!
06-29 11:59:34.050  22524-22524/com.thaifasttel D/dalvikvm﹕ newInstance failed: no <init>()
06-29 11:59:34.052  22524-22524/com.thaifasttel D/AndroidRuntime﹕ Shutting down VM
06-29 11:59:34.052  22524-22524/com.thaifasttel W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x40d6f9a8)
06-29 11:59:34.060  22524-22524/com.thaifasttel E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.thaifasttel/com.thaifasttel.MainActivity}: android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment com.thaifasttel.MainActivity$PlaceholderFragment: make sure class name exists, is public, and has an empty constructor that is public
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2343)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
            at android.app.ActivityThread.access$600(ActivityThread.java:162)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
            at android.os.Handler.dispatchMessage(Handler.java:107)
            at android.os.Looper.loop(Looper.java:194)
            at android.app.ActivityThread.main(ActivityThread.java:5371)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment com.thaifasttel.MainActivity$PlaceholderFragment: make sure class name exists, is public, and has an empty constructor that is public
            at android.support.v4.app.Fragment.instantiate(Fragment.java:413)
            at android.support.v4.app.FragmentState.instantiate(Fragment.java:97)
            at android.support.v4.app.FragmentManagerImpl.restoreAllState(FragmentManager.java:1801)
            at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:213)
            at android.support.v7.app.ActionBarActivity.onCreate(ActionBarActivity.java:97)
            at com.thaifasttel.MainActivity.onCreate(MainActivity.java:73)
            at android.app.Activity.performCreate(Activity.java:5122)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
            at android.app.ActivityThread.access$600(ActivityThread.java:162)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
            at android.os.Handler.dispatchMessage(Handler.java:107)
            at android.os.Looper.loop(Looper.java:194)
            at android.app.ActivityThread.main(ActivityThread.java:5371)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.InstantiationException: can't instantiate class com.thaifasttel.MainActivity$PlaceholderFragment; no empty constructor
            at java.lang.Class.newInstanceImpl(Native Method)
            at java.lang.Class.newInstance(Class.java:1319)
            at android.support.v4.app.Fragment.instantiate(Fragment.java:402)
            at android.support.v4.app.FragmentState.instantiate(Fragment.java:97)
            at android.support.v4.app.FragmentManagerImpl.restoreAllState(FragmentManager.java:1801)
            at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:213)
            at android.support.v7.app.ActionBarActivity.onCreate(ActionBarActivity.java:97)
            at com.thaifasttel.MainActivity.onCreate(MainActivity.java:73)
            at android.app.Activity.performCreate(Activity.java:5122)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
            at android.app.ActivityThread.access$600(ActivityThread.java:162)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
            at android.os.Handler.dispatchMessage(Handler.java:107)
            at android.os.Looper.loop(Looper.java:194)
            at android.app.ActivityThread.main(ActivityThread.java:5371)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
            at dalvik.system.NativeStart.main(Native Method)

---

您能否从程序中进一步演示如何初始化和使用webview..类

com.thaifasttel.MainActivity$PlaceholderFragment

必须有一个没有参数的构造函数。我有public PlaceholderFragment（）。这是否意味着我已经有了没有参数的构造函数？您应该将

占位符片段

移动到一个单独的文件中，并将其公开

public class MainActivity extends ActionBarActivity {


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

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment())
                    .commit();
        }

    }


    @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();
        return id == R.id.action_settings || super.onOptionsItemSelected(item);
    }

    public class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            Log.e("My App", "onCreateView");
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            return rootView;
        }

        WebView myWebView;
        RelativeLayout splash_view;
        TextView splash_text;
        SharedPreferences Usettings;
        String lang="th";
        int isloadwa=0;
        AssetManager assetPath = getAssets();
        String waAssetPath ="web";
        String wabase=getApplicationContext().getFilesDir().getPath();
        String waIntPath = "web";
        String waIntPath2 = wabase+"/"+waIntPath;
        String baseupdatefolder="http://www.test.com/test/webapp";

        @Override
        public void onActivityCreated(Bundle savedInstanceState) {
            super.onActivityCreated(savedInstanceState);
            Log.e("My App", "onActivityCreated");
            myWebView = (WebView) getView().findViewById(R.id.webview);
            splash_view = (RelativeLayout) getView().findViewById(R.id.splashview);
            splash_text = (TextView) getView().findViewById(R.id.splash_status);
            inituserPref();
            copydir();
        }

        @Override
        public void onStart(){
            super.onStart();
            Log.e("My App", "onstart");
        }

        @Override
        public void onResume(){
            super.onResume();
            Log.e("My App", "onResume");
            if(isloadwa==1) {
                if (isConnected()) {
                    Log.e("My App", "check update in app");
                    splash_text.setText(a_check_update);
                    checkupdate();
                }
            }
        }

        // do a lot of method after this