[英]onclicklistener doesn't work on fragment - android studio
問候語當我在片段上單擊TextView時,應用程序崩潰。 請我需要專業知識來幫助我修復它。 我已經在互聯網上閱讀了很多書,但還沒有解決方案,我嘗試了許多方法,但都無法解決我的問題
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:關閉VM 06-01 13:14:28.608 4559-4559 / com.example.mymachine.nav1 E / AndroidRuntime:FATAL例外:主進程:com.example.mymachine.nav1,PID:4559 java.lang.RuntimeException:無法啟動活動ComponentInfo {com.example.mymachine.nav1 / com.example.mymachine.nav1.Main2Activity}:java.lang .NullPointerException:嘗試在android.app上的android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)上的空對象引用上調用虛擬方法'android.view.View android.view.View.findViewById(int)'。 android.app.ActivityThread.-wrap12(ActivityThread.java)(位於android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1477)位於android.os.Handler.dispatchMessage()上的ActivityThread.handleLaunchActivity(ActivityThread.java:2726) android.os.Looper.loop(Looper.java:154)處的Handler.java:102)java.lang.reflect.Method.invoke(android.app.ActivityThread.main(ActivityThread.java:6119)處的Handler.java:102) com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:886)處的com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)處的本機方法)原因:java.lang。 NullPointerException:嘗試在android.com.example.mymachine.nav1.Main2Activity.onCreate(Main2Activity.java:17)上的空對象引用上調用虛擬方法'android.view.View android.view.View.findViewById(int)' android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)位於android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)位於android.app.ActivityThread處的.app.Activity.performCreate(Activity.java:6679) android.app.ActivityThread上的handleLaunchActivity(ActivityThread.java:2726)-android.os.Handler.dispatchMessage(Handler)上的android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1477)的wrap12(ActivityThread.java) java.102在android.os.Looper.loop(Looper.java:154)在android.app.ActivityThread.main(ActivityThread.java:6119)在java.lang.r com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:886)上的eflect.Method.invoke(本機方法),com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)上的eflect.Method.invoke(本機方法)
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>
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);
}
如果有幫助,請嘗試此操作
@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;
}
}
檢查以下代碼:
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);
}
}
您可以在xml(For Textview)中設置點擊處理程序:
android:onClick="onClick" android:clickable="true"
在您的活動中:
public class yourActivity extends Activity {
public void onClick(View v) {
...
}
}
最后,我已經解決了問題
最后一個錯誤是Nullpointer,並且無法開始活動
我轉到main2activity.java並執行以下操作:
1-刪除
private TextView textview;
private View view;
改變以下
textView = (TextView) view.findViewById(R.id.textView2);
至
TextView textView = (TextView) findViewById(R.id.textView2);
我的應用程序現在可以正常工作了。
感謝所有借我時間幫助我的人。 在另一個問題上見。
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