Java 如何在片段中创建自定义listview
我当前希望创建一个自定义listview,将其放置在我创建的其中一个片段中,该片段当前是我的Homefragment.java文件,如下所示:Java 如何在片段中创建自定义listview,java,android,listview,android-fragments,Java,Android,Listview,Android Fragments,我当前希望创建一个自定义listview,将其放置在我创建的其中一个片段中,该片段当前是我的Homefragment.java文件,如下所示: package sg.edu.rp.c346.a3pdwork; import android.os.Bundle; import androidx.fragment.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android
package sg.edu.rp.c346.a3pdwork;
import android.os.Bundle;
import androidx.fragment.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
/**
* A simple {@link Fragment} subclass.
*/
public class HomeFragment extends Fragment {
public HomeFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_home, container, false);
String[] menuItems = {"Bob Contact: 99999999 ", "Alan Contact: 88888888", "Ryan Contact: 77777777"};
ListView listView = (ListView) view.findViewById(R.id.listViewDetails);
ArrayAdapter<String> listViewAdapter = new ArrayAdapter<String>(
getActivity(),
android.R.layout.simple_list_item_1,
menuItems
);
listView.setAdapter(listViewAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if (position == 0) {
Toast.makeText(getActivity(),"Hi! You CLikced the first item", Toast.LENGTH_LONG).show();
}else if (position == 1) {
Toast.makeText(getActivity(),"Hi! You CLikced the Second item", Toast.LENGTH_LONG).show();
}else if (position == 2) {
Toast.makeText(getActivity(),"Hi! You CLikced the Third item", Toast.LENGTH_LONG).show();
}
}
});
// Inflate the layout for this fragment
return view;
}
}
您正在通过一个空的ogject(即listview)调用
setAdapter()
。我估计您的片段布局文件fragment\u home.xml
中没有listViewDetails
ListView。因此,请尝试将listview放在布局文件中。在homefragment中创建自定义listview时,显示listview所在的xml并显示所有错误。@HaroldSer抱歉,但我被您的陈述弄糊涂了抱歉,我已经创建了一个listview,它是我的片段\u home.xml文件,如下所示:``但我是吗错过了别的地方?很抱歉,因为我对这个还很陌生
--------- beginning of crash
2020-02-09 11:10:56.883 14328-14328/sg.edu.rp.c346.a3pdwork E/AndroidRuntime: FATAL EXCEPTION: main
Process: sg.edu.rp.c346.a3pdwork, PID: 14328
java.lang.RuntimeException: Unable to start activity ComponentInfo{sg.edu.rp.c346.a3pdwork/sg.edu.rp.c346.a3pdwork.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at sg.edu.rp.c346.a3pdwork.MainActivity.onCreate(MainActivity.java:55)
at android.app.Activity.performCreate(Activity.java:7136)
at android.app.Activity.performCreate(Activity.java:7127)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)