java.lang.NoSuchMethodException for onCreate

问题

I see crashes in the Google Play crash log that is really stumping me.

java.lang.RuntimeException: 
  at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:3086)
  at android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:3229)
  at android.app.servertransaction.LaunchActivityItem.execute (LaunchActivityItem.java:78)
  at android.app.servertransaction.TransactionExecutor.executeCallbacks (TransactionExecutor.java:108)
  at android.app.servertransaction.TransactionExecutor.execute (TransactionExecutor.java:68)
  at android.app.ActivityThread$H.handleMessage (ActivityThread.java:1926)
  at android.os.Handler.dispatchMessage (Handler.java:106)
  at android.os.Looper.loop (Looper.java:214)
  at android.app.ActivityThread.main (ActivityThread.java:6981)
  at java.lang.reflect.Method.invoke (Native Method)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:493)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1445)
Caused by: androidx.fragment.app.Fragment$InstantiationException: 
  at androidx.fragment.app.Fragment.instantiate (Fragment.java:462)
  at androidx.fragment.app.FragmentContainer.instantiate (FragmentContainer.java:50)
  at androidx.fragment.app.FragmentState.instantiate (FragmentState.java:80)
  at androidx.fragment.app.FragmentManagerImpl.restoreAllState (FragmentManager.java:3109)
  at androidx.fragment.app.FragmentController.restoreAllState (FragmentController.java:158)
  at androidx.fragment.app.FragmentActivity.onCreate (FragmentActivity.java:344)
  at androidx.appcompat.app.AppCompatActivity.onCreate (AppCompatActivity.java:85)
  at com.autotask.jbarra.kotlinmvvm.MainActivity.onCreate (MainActivity.kt:102)
  at android.app.Activity.performCreate (Activity.java:7326)
  at android.app.Activity.performCreate (Activity.java:7317)
  at android.app.Instrumentation.callActivityOnCreate (Instrumentation.java:1271)
  at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:3066)

Caused by: java.lang.NoSuchMethodException: 
  at java.lang.Class.getConstructor0 (Class.java:2328)
  at java.lang.Class.getConstructor (Class.java:1725)
  at androidx.fragment.app.Fragment.instantiate (Fragment.java:443)

the thing is, line 102 of Main activity is nothing special

    override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState) //This is line 102

What could cause this? Why is oncreate throwing no such method? It's happening on a few user's devices and I haven't been able to reproduce it.

回答1:

The activity is being restored from an instance state bundle. Part of the restore operation is recreating its fragments.

Your activity has a fragment and the fragment class does not have a 0-arg constructor required by the framework.

回答2:

My Activity had a FragmentPagerAdapter that was using the deperecated constructor. I changed

class MyPagerAdapter(
        fragmentManager: FragmentManager,
        private val myActivity: MyActivity
    ) : FragmentPagerAdapter(fragmentManager) // DEPRECATED

class MyPagerAdapter(
        fragmentManager: FragmentManager,
        private val myActivity: MyActivity
    ) : FragmentPagerAdapter(fragmentManager, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT)

Seem to have fixed the problem

回答3:

After some search i finally fix the issue. You have to check 3 things.

You should have a 0-arg constructor in the fragment, best practice is to do something like bellow
If you are using callback in the caller, you have to check if getContext is null or not (otherwise you will get a NullPointerException)
Don't forget to test the case when the screen orientation change, this will allow you to reproduce some potential issue due to restoring fragment state

Sample code example :

    public class MyDialogFragment extends DialogFragment{
     private String id;

     public static MyDialogFragment newInstance(String id) {
        MyDialogFragment f = new MyDialogFragment ();

        Bundle args = new Bundle();
        if(id!= null){
            args.putString("id", id);
        }
        f.setArguments(args);

        return f;
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if(savedInstanceState != null){
            id= savedInstanceState.getString("id");
        }
    }
    }

来源：https://stackoverflow.com/questions/56668934/java-lang-nosuchmethodexception-for-oncreate

标签

java

android

android-fragments

kotlin