我试图触发一个mp3声音来按下listView中的按钮。该应用程序编译好并生成APK。但是当开始休息时。
这是活动：
MainActivity.java
public class MainActivity extends Activity {
MediaPlayer player;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//string data
String[] myStringArray={
"ANGUS PREMIUM DELUXE",
"ANGUS PREMIUM BACON",
"CUARTO DE LIBRA CON QUESO",
"DOBLE CUARTO DE LIBRA CON QUESO",
"McNÍFICA",
"TRIPLE MAC",
"BIG MAC",
"McFIESTA",
"HAMBURGUESA CON QUESO",
"HAMBURGUESA"
};
//adapter
ArrayAdapter<String> myAdapter = new ArrayAdapter<String>(
this,
// android.R.layout.simple_list_item_1,
// R.layout.mylayout,
R.layout.mylayout2,
R.id.btnAddItem2,
myStringArray);
//asociate
ListView myList =
(ListView) findViewById(R.id.listView);
assert myList != null;
myList.setAdapter(myAdapter);
//sound
Button btnAddItem = (Button) findViewById(R.id.btnAddItem2);
btnAddItem.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//player = MediaPlayer.create(MainActivity.this, R.raw.snd_add_payment);
//player.start();
}
});
}
}
这是包含重复行的布局：
mylayout2.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical" >
<Button
android:id="@+id/btnAddItem2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="test" />
</LinearLayout>
登录崩溃
--------- beginning of crash
06-19 23:53:30.030 2921-2921/moalaiskirulais.com.arrayadapter E/AndroidRuntime: FATAL EXCEPTION: main
Process: moalaiskirulais.com.arrayadapter, PID: 2921
java.lang.RuntimeException: Unable to start activity ComponentInfo{moalaiskirulais.com.arrayadapter/moalaiskirulais.com.arrayadapter.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at moalaiskirulais.com.arrayadapter.MainActivity.onCreate(MainActivity.java:68)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
06-19 23:53:30.075 1565-2093/system_process W/ActivityManager: Force finishing activity moalaiskirulais.com.arrayadapter/.MainActivity
答案 0 :(得分：1)
您的btnAddItem2中没有按钮activity_main.xml
将其添加到activity_main.xml：
<include layout="@layout/mylayout2" />
答案 1 :(得分：1)
我认为cricket_007是对的。如果要控制列表中每个项目的视图，则必须创建如下自定义类：
<强> CustomArrayAdapter
public class CustomArrayAdapter extends ArrayAdapter<String> {
private ArrayList<String> yourList; // for set data to list.
private LayoutInflater inflater = null; // for access your views.
private int layoutResId;
public CustomArrayAdapter(Context c, int resId, ArrayList<String> list) {
super(c, resId);
layoutResId = resId;
yourList = list;
this.inflater = LayoutInflater.from(c);
}
@Override
public int getCount() {
return yourList.size();
}
public void setData(ArrayList<String> list) {
yourList = list;
}
@Override
public view getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
View view = convertView;
if (view == null) {
view = this.inflater.inflate(layoutResId, null); // inflate your custom layout for list.
holder = new ViewHolder();
view.setTag(holder);
} else {
holder = (ViewHolder)view.getTag();
}
holder.button = (Button)view.findViewById(R.id.btnAddItem2);
holder.button.setText(yourList.get(position).getName());
holder.button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// make your button event.
}
});
return view;
}
static class ViewHolder {
private Button button;
}
}
然后，尝试将此适配器设置为列表视图。
<强> MainActivity
// custom adapter
ArrayAdapter<String> myAdapter = new CustomArrayAdapter<String>(
MainActivity.this,
R.layout.mylayout2,
myStringArray);
//asociate
ListView myList =
(ListView) findViewById(R.id.listView);
assert myList != null;
myList.setAdapter(myAdapter);