Question

问候语当我点击片段上的TextView时，应用程序崩溃了。我需要专业知识来帮助我解决它。我在互联网上读了许多但没有解决方案，我尝试了很多方法，但都无法解决我的问题

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);
                }
             }
        );

    }
*/

}

下面是logcat：

06-01 13：14：28.607 4559-4559 / com.example.mymachine.nav1 D / AndroidRuntime：关闭VM 06-01 13：14：28.608 4559-4559 / com.example.mymachine.nav1 E / AndroidRuntime：FATAL EXCEPTION：main 处理：com.example.mymachine.nav1，PID：4559 java.lang.RuntimeException：无法启动活动ComponentInfo {com.example.mymachine.nav1 / com.example.mymachine.nav1.Main2Activity}：java.lang.NullPointerException：尝试调用虚拟方法'android.view.View android。在null对象引用上查看.View.findViewById（int）' 在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2665）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2726）在android.app.ActivityThread.-wrap12（ActivityThread.java）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1477）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:154）在android.app.ActivityThread.main（ActivityThread.java:6119） at java.lang.reflect.Method.invoke（Native Method）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:886）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:776）引起：java.lang.NullPointerException：尝试在空对象引用上调用虚方法'android.view.View android.view.View.findViewById（int）' 在com.example.mymachine.nav1.Main2Activity.onCreate（Main2Activity.java:17）在android.app.Activity.performCreate（Activity.java:6679）在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1118）在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2618）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2726）在android.app.ActivityThread.-wrap12（ActivityThread.java）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1477）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:154）在android.app.ActivityThread.main（ActivityThread.java:6119） at java.lang.reflect.Method.invoke（Native Method）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:886）在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

如果有帮助，试试这个，

@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

检查以下代码：

 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

您可以在xml中设置点击处理程序（对于您的Textview）：

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

在您的活动中：

public class yourActivity extends Activity {

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

Answer 5

最后，我已经解决了问题

最后一个错误是Nullpointer＆amp;无法开展活动

我转到main2activity.java并执行以下操作：

1-删除

private TextView textview;
private View view;

更改以下内容

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

到

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

我的应用现在工作正常。

感谢所有借我的时间来帮助我的人。在另一个问题中见到你。

onclicklistener不适用于片段 - android studio

5 个答案: