Fragment Home键返回桌面再打开程序，无法开启

最新推荐文章于 2021-11-28 23:16:56 发布

kim..

最新推荐文章于 2021-11-28 23:16:56 发布

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文章标签： Android Fragment Slidingmenu

本文链接：https://blog.youkuaiyun.com/happyboylk/article/details/51675625

当使用Fragment时，遇到启动应用后无法正常开启的情况，问题可能出在Fragment的构造函数上。删除空的构造函数或者确保有一个公共的无参构造函数可以解决此问题。参考Stack Overflow上的解答，推荐通过静态方法newInstance来创建并传递参数。

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与上次onCreate、onCreateView中初始化Textview导致错误不同：

查阅资料发现，这次是因为构造函数有问题造成的，仔细检查代码发现确实是有个空的构造函数，删除后无报错。

可参考： http://stackoverflow.com/questions/10450348/do-fragments-really-need-an-empty-constructor

最佳答案：You shouldn't really be overriding the constructor anyway. You should have a newInstance() static method defined and pass any parameters via arguments (bundle)

例如：

public static final AlertFragment newInstance(int title, String message){
    AlertFragment f = new AlertFragment();
    Bundle bdl = new Bundle(2);
    bdl.putInt(EXTRA_TITLE, title);
    bdl.putString(EXTRA_MESSAGE, message);
    f.setArguments(bdl);
    return f;}

运行日志报错内容；

java.lang.RuntimeException: Unable to start activity ComponentInfo{xxx.cscc/xxx.cscc.activity.MainActivity}: android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment xxx.cscc.fragment.cert.CerApplyingFragment: make sure class name exists, is public, and has an empty constructor that is public

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2406)

at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2466)

at android.app.ActivityThread.access$1200(ActivityThread.java:152)

at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1341)

at android.os.Handler.dispatchMessage(Handler.java:102)

at android.os.Looper.loop(Looper.java:135)

at android.app.ActivityThread.main(ActivityThread.java:5539)

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:960)

at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

Caused by: android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment xxx.cscc.fragment.cert.CerApplyingFragment: make sure class name exists, is public, and has an empty constructor that is public

at android.support.v4.app.Fragment.instantiate(Fragment.java:417)

at android.support.v4.app.FragmentState.instantiate(Fragment.java:97)

at android.support.v4.app.FragmentManagerImpl.restoreAllState(FragmentManager.java:1790)

at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:213)

at com.jeremyfeinstein.slidingmenu.lib.app.SlidingFragmentActivity.onCreate(SlidingFragmentActivity.java:20)

at xxx.cscc.activity.MainActivity.onCreate(MainActivity.java:38)

at android.app.Activity.performCreate(Activity.java:6013)

at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2359)

at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2466)

at android.app.ActivityThread.access$1200(ActivityThread.java:152)

at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1341)

at android.os.Handler.dispatchMessage(Handler.java:102)

at android.os.Looper.loop(Looper.java:135)

at android.app.ActivityThread.main(ActivityThread.java:5539)

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:960)

at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

Caused by: java.lang.IllegalAccessException: private xxx.cscc.fragment.cert.CerApplyingFragment() is not accessible from class android.support.v4.app.Fragment

at java.lang.Class.newInstance(Class.java:1569)

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:1790)

at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:213)

at com.jeremyfeinstein.slidingmenu.lib.app.SlidingFragmentActivity.onCreate(SlidingFragmentActivity.java:20)

at xxx.cscc.activity.MainActivity.onCreate(MainActivity.java:38)

at android.app.Activity.performCreate(Activity.java:6013)

at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2359)

at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2466)

at android.app.ActivityThread.access$1200(ActivityThread.java:152)