我有2个类,它们被片段覆盖。home.javahometwo.java
单击我的名为home.java的类的名为btn的按钮。我希望自动在名为btnctwo的按钮上单击名为hometwo.java的类。
home.java
public class home extends Fragment {
Button btn;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.home, container, false);
btn = rootView.findViewById(R.id.btnc);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
hometwo hometwox = new hometwo();
hometwox.btnctwo
.post(new Runnable(){
@Override
public void run() {
hometwox.btnctwo.performClick();
}
});
}
});
return rootView;
}
}
hometwo.java
public class hometwo extends Fragment {
Button btnctwo;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.home, container, false);
btnctwo = rootView.findViewById(R.id.btnctwo);
btnctwo.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.e("testler","testlertwo");
}
});
return rootView;
}
}
logcat
2020-05-18 11:17:54.907 11290-11290/com.sahnartsappone.sahnartsapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.sahnartsappone.sahnartsapp, PID: 11290
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.widget.Button.post(java.lang.Runnable)' on a null object reference
at com.sahnartsappone.sahnartsapp.home$1.onClick(home.java:30)
at android.view.View.performClick(View.java:7125)
at android.view.View.performClickInternal(View.java:7102)
at android.view.View.access$3500(View.java:801)
at android.view.View$PerformClick.run(View.java:27336)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
为什么performClick()方法不起作用?我在哪里犯错?
问题在这里:
hometwo hometwox = new hometwo();
hometwox.btnctwo
.post...
[如果仅创建片段,它将无法使用onCreateView
方法,因此不会将btnctwo
中的hometwox
按钮与视图中的按钮实例一起注入(因为将不会有任何视图) 。
所以解决方案是使用类似以下内容的片段:
FragmentTransaction transaction = this.fragmentManager.beginTransaction();
transaction.replace(R.id.frame_container, fragment);
transaction.addToBackStack(null);
transaction.commit();