Java 为什么在将数据从一个片段发送到另一个片段时出错

我读过这些问题和许多其他问题，但没有人能轻松解释

嗨，我对编程和stackoverflow很陌生

我创建了一个MainActivity，其中有两个片段

<fragment
    android:id="@+id/fragment1"
    android:name="fragments.first"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1">

</fragment>

<fragment
    android:id="@+id/fragment2"
    android:name="fragments.second"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1">
</fragment>

但接收误差

2021-05-04 03:19:28.676 23166-23166/com.example.mcqapp E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.mcqapp, PID: 23166
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mcqapp/com.example.mcqapp.activities.AdminPost}: android.view.InflateException: Binary XML file line #25 in com.example.mcqapp:layout/activity_admin_post: Binary XML file line #25 in com.example.mcqapp:layout/activity_admin_post: Error inflating class fragment
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3556)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3703)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2216)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:237)
        at android.app.ActivityThread.main(ActivityThread.java:7948)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075)
     Caused by: android.view.InflateException: Binary XML file line #25 in com.example.mcqapp:layout/activity_admin_post: Binary XML file line #25 in com.example.mcqapp:layout/activity_admin_post: Error inflating class fragment
     Caused by: android.view.InflateException: Binary XML file line #25 in com.example.mcqapp:layout/activity_admin_post: Error inflating class fragment
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
        at fragments.second.onCreate(second.java:20)
        at androidx.fragment.app.Fragment.performCreate(Fragment.java:2586)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:838)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1133)
        at androidx.fragment.app.FragmentManagerImpl.addFragment(FragmentManagerImpl.java:1393)
        at androidx.fragment.app.FragmentManagerImpl.onCreateView(FragmentManagerImpl.java:3205)
        at androidx.fragment.app.FragmentController.onCreateView(FragmentController.java:134)
        at androidx.fragment.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:357)
        at androidx.fragment.app.FragmentActivity.onCreateView(FragmentActivity.java:336)
        at android.view.LayoutInflater.tryCreateView(LayoutInflater.java:1069)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:997)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:961)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:1123)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:1126)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:682)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:534)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:481)
        at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:696)
        at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:170)
        at com.example.mcqapp.activities.AdminPost.onCreate(AdminPost.java:24)
        at android.app.Activity.performCreate(Activity.java:7955)
        at android.app.Activity.performCreate(Activity.java:7944)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3531)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3703)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
2021-05-04 03:19:28.677 23166-23166/com.example.mcqapp E/AndroidRuntime:     at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2216)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:237)
        at android.app.ActivityThread.main(ActivityThread.java:7948)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075)

---

我解决了。我从活动中删除了第二个片段，并将第一个片段转换为框架布局，因为数据重叠，并以编程方式添加了第一个片段

<FrameLayout
    android:id="@+id/fragment1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

</FrameLayout>

getSupportFragmentManager().beginTransaction().add(R.id.fragment1,new first()).commit();

---

我读了很多StackOverflow问题，并使用了框架布局，因为重叠正在发生，对吗？

当活动启动时，您已经在活动中加载了这两个片段。因此，一旦创建了这两个片段，您期望参数

“Question1”

的片段就会失败，因为bundle将为null，因为没有向它发送参数。因此出现了NullPointerException，那么如何解决它呢？正如错误日志中提到的，布局名称activity_admin_post在第25行中有一个错误，这就是它导致崩溃的原因。检查布局文件并首先解决问题。如果我在第二个片段上注释掉捆绑包，代码将毫无错误地开始，然后返回到第一个。问题是bundle为null。但不应该，因为我还没有按下按钮

2021-05-04 03:19:28.676 23166-23166/com.example.mcqapp E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.mcqapp, PID: 23166
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mcqapp/com.example.mcqapp.activities.AdminPost}: android.view.InflateException: Binary XML file line #25 in com.example.mcqapp:layout/activity_admin_post: Binary XML file line #25 in com.example.mcqapp:layout/activity_admin_post: Error inflating class fragment
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3556)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3703)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2216)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:237)
        at android.app.ActivityThread.main(ActivityThread.java:7948)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075)
     Caused by: android.view.InflateException: Binary XML file line #25 in com.example.mcqapp:layout/activity_admin_post: Binary XML file line #25 in com.example.mcqapp:layout/activity_admin_post: Error inflating class fragment
     Caused by: android.view.InflateException: Binary XML file line #25 in com.example.mcqapp:layout/activity_admin_post: Error inflating class fragment
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
        at fragments.second.onCreate(second.java:20)
        at androidx.fragment.app.Fragment.performCreate(Fragment.java:2586)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:838)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1133)
        at androidx.fragment.app.FragmentManagerImpl.addFragment(FragmentManagerImpl.java:1393)
        at androidx.fragment.app.FragmentManagerImpl.onCreateView(FragmentManagerImpl.java:3205)
        at androidx.fragment.app.FragmentController.onCreateView(FragmentController.java:134)
        at androidx.fragment.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:357)
        at androidx.fragment.app.FragmentActivity.onCreateView(FragmentActivity.java:336)
        at android.view.LayoutInflater.tryCreateView(LayoutInflater.java:1069)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:997)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:961)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:1123)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:1126)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:682)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:534)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:481)
        at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:696)
        at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:170)
        at com.example.mcqapp.activities.AdminPost.onCreate(AdminPost.java:24)
        at android.app.Activity.performCreate(Activity.java:7955)
        at android.app.Activity.performCreate(Activity.java:7944)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3531)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3703)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
2021-05-04 03:19:28.677 23166-23166/com.example.mcqapp E/AndroidRuntime:     at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2216)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:237)
        at android.app.ActivityThread.main(ActivityThread.java:7948)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075)

<FrameLayout
    android:id="@+id/fragment1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

</FrameLayout>

getSupportFragmentManager().beginTransaction().add(R.id.fragment1,new first()).commit();

Bundle bundle = getArguments();
if (bundle != null){

    String question = bundle.getString("Question1");
    String Question  = question.toString();
    textView.setText(Question);