如何使用 Bundle() 将值从 1 个片段传递到另一个片段？

Question

I found this code to pass the data from a fragment to another:

Fragment 1:

    FragmentManager fragmentManager = getFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    Fragment2 fragment2 = new Fragment2();
    Bundle bundle = new Bundle();
    bundle.putString("data", data);
    fragmentTransaction.replace(R.id.fragment_container, fragment2);
    fragmentTransaction.addToBackStack(null);
    fragmentTransaction.commit();

Fragment 2:

   Bundle bundle = getArguments();
   assert bundle != null;
   String data = bundle.getString("data");

But I dont want to change the fragment. So I removed parts of it. But it doesnt work. Here my code:

Fragment 1:

public void openActifity2(){
    Fragment_score fragment_score = new Fragment_score();
    Bundle bundle = new Bundle();
    bundle.putInt("FINISHED_LEVELS", finishedLevels);
    bundle.putInt("FAILED_LEVELS", failedLevels);
    bundle.putInt("SKIPPED_LEVELS", skippedLevels);
    bundle.putInt("USED_HINTS", usedHints);
    fragment_score.setArguments(bundle);
}

Fragment 2:

    Bundle bundle = getArguments();
    int finishedLevels = bundle.getInt("FINISHED_LEVELS");
    int failedLevels = bundle.getInt("FINISHED_LEVELS");
    int skippedLevels = bundle.getInt("FINISHED_LEVELS");
    int usedHints = bundle.getInt("FINISHED_LEVELS");

Do I have to use the code I found on the internet or does my version work too? I get this error when I open the second fragment:

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.rexan_snerficonquiz, PID: 20931 java.lang.NullPointerException: Attempt to invoke virtual method 'int android.os.Bundle.getInt(java.lang.String)' on a null object reference at com.example.rexan_snerficonquiz.Fragment_score.onCreateView(Fragment_score.java:26) at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600) at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881) at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238) at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303) a t androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:439) at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2079) at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869) at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824) at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727) at androidx.fragment.app.FragmentManagerImpl$2.run(FragmentManagerImpl.java:150) at android.os.Handler.handleCallback(Handler.java:938) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.l oop(Looper.java:223) at android.app.ActivityThread.main(ActivityThread.java:7523) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:941)

Answer 1

in order to avoid getting the error, try this

Bundle bundle = getArguments();
if(bundle != null){
    int finishedLevels = bundle.getInt("FINISHED_LEVELS", "DEFAULT_VALUE");
    int failedLevels = bundle.getInt("FINISHED_LEVELS", "DEFAULT_VALUE");
    int skippedLevels = bundle.getInt("FINISHED_LEVELS", "DEFAULT_VALUE");
    int usedHints = bundle.getInt("FINISHED_LEVELS", "DEFAULT_VALUE");
}

Based on your comments, you can change fragment in onOptionsItemSelected method

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    int id = item.getItemId();

    if (id == R.id.action_1) {
        // add your action here that you want
        return true;
    }else if (id==R.id.action_2) {
         // add your action here that you want
        return true;
    }

    return super.onOptionsItemSelected(item);
} 

Answer 2

If you change the fragments than your code will be working fine. But if you don't want to change fragments than 1) int finishedLevels = bundle.getInt("FINISHED_LEVELS", 0); OR 2) Instead of bundle use static global variables public static int finishedLevels = 0; in Fragment 1 and then simply get their value in Fragment 2 using class name reference. Note: If you don't want to change the fragment and want values in Fragment 2 then i would recommend the static variables