onclicklistener不适用于片段-Android Studio

Question

Greeting When I click on TextView on the fragment, the app is crash. Please I need the expertise to help me to fix it. I have read many in the internet but no solution yet and I try many ways and all are not able to solve mine

package com.example.mymahine.nav1;

import android.app.Activity;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.VelocityTrackerCompat;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;


/**
 * A simple {@link Fragment} subclass.
 */
public class CameraFragment extends Fragment implements onClickListener{
private TextView textView;
    public CameraFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_camera, container, false);
        TextView textview = (TextView) view.findViewById(R.id.frag_text);
        textview.setOnClickListener(new onClickListener);
        // Inflate the layout for this fragment

        return view;


    }

    @Override
    public void onClick(View v){
        Intent intent = new Intent(getActivity(), Main2Activity.class);
        startActivity(intent);
    }

/*
    public void onActivityCreated(Bundle savedInstanceState)
    {
        // TODO Auto-generated method stub
        super.onActivityCreated(savedInstanceState);


        TextView tv2 = (TextView) getActivity().findViewById(R.id.textView1);
        tv2.setOnClickListener(new view2.OnClickListener() {
            public void onClick(View v) {

                Intent intent = new Intent(getActivity(), Main2Activity.class);
                startActivity(intent);
                }
             }
        );

    }
*/

}

Below is logcat:

06-01 13:14:28.607 4559-4559/com.example.mymachine.nav1 D/AndroidRuntime: Shutting down VM 06-01 13:14:28.608 4559-4559/com.example.mymachine.nav1 E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.mymachine.nav1, PID: 4559 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mymachine.nav1/com.example.mymachine.nav1.Main2Activity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6119) at java.lang.reflect.Method.invoke( Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference at com.example.mymachine.nav1.Main2Activity.onCreate(Main2Activity.java:17) at android.app.Activity.performCreate(Activity.java:6679) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6119) at java.lang.r eflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

fragment_camera.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.shakeralmoosa.nav1.CameraFragment">

<!-- TODO: Update blank fragment layout -->

<TextView
    android:id="@+id/frag_text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="195dp"
    android:text="GO TO NEXT ACTIVITY"
    android:textAlignment="center"
    android:textSize="30sp"
    android:clickable="true"
    android:onClick="onClick"
    android:focusable="true"
    android:focusableInTouchMode="true"/>
    </LinearLayout>

Answer 1

1    Replace your code with this:

    public class CameraFragment extends Fragment implements View.OnClickListener{
    public CameraFragment() {
        // Required empty public constructor
    }

@Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,@Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_camera, container, false);
    TextView textview = (TextView) view.findViewById(R.id.frag_text);
    textView.setOnClickListener(this);
    return view;
}

@Override
    public void onClick(View v){
        Intent intent = new Intent(getActivity(), Main2Activity.class);
        startActivity(intent);
    }

Answer 2

Try this if it helps,

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_camera, container, false);
        TextView textview = (TextView) view.findViewById(R.id.frag_text);
        textview.setOnClickListener(this);
        // Inflate the layout for this fragment

        return view;


    }

      @Override
    public void onClick(View v) {
     switch(v.getId()){

     case R.id.frag_text :
         //your code...
         Intent intent = new Intent(getActivity(), Main2Activity.class);
         startActivity(intent);
     break;

    default:
        break;

     }

    }

Answer 3

check below code:

 public class CameraFragment extends Fragment implements View.OnClickListener{
        private TextView textView;
        public CameraFragment() {
            // Required empty public constructor
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View view = inflater.inflate(R.layout.fragment_camera, container, false);
            TextView textview = (TextView) view.findViewById(R.id.frag_text);
            textview.setOnClickListener(this);
            // Inflate the layout for this fragment
            return view;
        }
        @Override
        public void onClick(View v){
            Intent intent = new Intent(getActivity(), Main2Activity.class);
            startActivity(intent);
        }


    }

Answer 4

You can set the click handler in xml(For your Textview) :

android:onClick="onClick" android:clickable="true"

In your Activity:

public class yourActivity extends Activity {

          public void onClick(View v) {
            ...
          }  
       }

Answer 5

Finally, I have resolved the problem

Last error was Nullpointer & can't activity started

I go to main2activity.java and do the followings:

1- remove

private TextView textview;
private View view;

change the following

textView = (TextView) view.findViewById(R.id.textView2);

to

TextView textView = (TextView) findViewById(R.id.textView2);

My app is working fine now.

Thanks for everybody who borrow me his time to help me. See you in another problem.