Android在Fragment中出现onClick监听器错误

Question

我在setOnLongClickListener中的fragment出错，这是我的代码和错误

Logcat

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.widget.TextView.findViewById(int)' on a null object reference
        at me.jatinsoni.myfragmentexample.BottomVIew.onCreateView(BottomVIew.java:23)

第23行： textView.findViewById(R.id.bottom_text);

片段类

import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;

public class BottomVIew extends Fragment {

    public View view;
    public TextView textView;
    public Button button;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.bottom_layout, container, false);

        textView.findViewById(R.id.bottom_text);
        button.findViewById(R.id.bottom_button);

        button.setOnLongClickListener(
                new Button.OnLongClickListener() {

                    @Override
                    public boolean onLongClick(View v) {
                        textView.setText(R.string.pressed_long);
                        return true;
                    }
                }
        );


        return view;
    }

}

布局代码

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="wrap_content">

    <TextView
        android:id="@+id/bottom_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:text="@string/bottom_view"
        android:textSize="30sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:fontFamily="serif"
        android:textColor="@android:color/black"/>

    <Button
        android:id="@+id/bottom_button"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="@string/click_to_update"
        app:layout_constraintTop_toBottomOf="@+id/bottom_text"
        app:layout_constraintStart_toStartOf="@id/bottom_text"
        app:layout_constraintEnd_toEndOf="@id/bottom_text"
        app:layout_constraintBottom_toBottomOf="parent"
        android:layout_marginTop="16dp"
        android:layout_marginBottom="16dp"
        android:background="@color/colorAccent"
        android:textColor="@android:color/white"/>
</android.support.constraint.ConstraintLayout>

Answer 1

应该会的，

textView = view.findViewById(R.id.bottom_text);

和

buttonView = view.findViewById(R.id.bottom_button);