使用导航从Android片段访问onClick

Question

我无法为片段中的按钮设置onClick侦听器。也许我的上下文有误，但我看不出来。

请在下面帮忙，我想我已经做好了，好吗？我以为我理解工作的背景，但在我看来，今天有效的东西第二天无效？

片段xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/colorPrimary"
tools:context=".OBWelcomeFragment">
<ImageView
android:id="@+id/imageView3"
android:layout_width="150dp"
android:layout_height="150dp"
android:src="@drawable/logo_main"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.08" />
<ScrollView
android:id="@+id/scrollView3"
android:layout_width="324dp"
android:layout_height="333dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.494"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/imageView3"
app:layout_constraintVertical_bias="0.594">
<TextView
android:id="@+id/tv_description_heading"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="@string/ob_welcome_text"
android:textColor="@color/cardview_light_background"
android:textSize="18sp" />
</ScrollView>
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:text="@string/app"
android:textColor="@color/cardview_light_background"
android:textSize="36sp"
app:layout_constraintBottom_toTopOf="@+id/scrollView3"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/imageView3"
app:layout_constraintVertical_bias="0.18" />
<Button
android:id="@+id/oBlocationButton"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="32dp"
android:layout_marginLeft="32dp"
android:layout_marginEnd="32dp"
android:layout_marginRight="32dp"
android:layout_marginBottom="32dp"
android:onClick="onClick"
android:text="Next"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/scrollView2" />
</androidx.constraintlayout.widget.ConstraintLayout>

相应的片段

import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentActivity;
import androidx.navigation.NavDirections;
import androidx.navigation.Navigation;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class OBWelcomeFragment extends Fragment implements View.OnClickListener {
public OBWelcomeFragment() {
// Required empty public constructor
}
public static OBWelcomeFragment newInstance(String param1, String param2) {
OBWelcomeFragment fragment = new OBWelcomeFragment();
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_o_b_welcome, container, false);
}
@Override
public void onClick(View v) {
NavDirections action = 
OBWelcomeFragmentDirections.actionOBWelcomeFragmentToOBLocationFragment3();
Navigation.findNavController(v).navigate(action);
}
}

错误

2020-02-27 12:43:50.375 15523-15523/com.app E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.app, PID: 15523
java.lang.IllegalStateException: Could not find method onClick(View) in a parent or ancestor 
Context for android:onClick attribute defined on view class 
androidx.appcompat.widget.AppCompatButton with id 'oBlocationButton'
at 
androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatView 
Inflater.java:436)
at 
androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflat .er.java:393)
at android.view.View.performClick(View.java:7259)
at android.view.View.performClickInternal(View.java:7236)
at android.view.View.access$3600(View.java:801)
at android.view.View$PerformClick.run(View.java:27892)
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)

如果你还需要什么，请告诉我？

Answer 1

问题是您正在同时执行这两项操作(尽管两者都不完整…(，实现OnClickListener，并在xml中定义了一个方法。做其中任何一个。

我将同时指定这两种方法，要只在xml中执行，您必须在xml而不是中指定onClick()方法

<Button
android:id="@+id/oBlocationButton"
....
android:onClick="onClick"/>

在您的片段中，只需创建以下方法：(不要实现侦听器(

public class OBWelcomeFragment extends Fragment {
....
// notice -> no override here..
public void onClick(View v) {

}
}

或者另一种方式：这次不要在xml中指定onClick，而是只查找按钮并设置监听器。

public class OBWelcomeFragment extends Fragment implements View.OnClickListener {
.....
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Button btn = view.findViewById(R.id.oBlocationButton);
btn.setOnClickListener(this);
}
@Override
public void onClick(View v) {
NavDirections action = OBWelcomeFragmentDirections.actionOBWelcomeFragmentToOBLocationFragment3();
Navigation.findNavController(v).navigate(action);
}
}