Android Listview Click crashes

Question

The below is my testing code to create the list view, the list view display successfully, however, there is error in click event. Here is my simple code:

public class MainActivity extends Activity {

    private String[] Ass;
    private TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);
         Ass=new String[]{"Ass1","Ass"};
        ListView mListView = (ListView) findViewById(R.id.ass);

        ArrayAdapter<String> mAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, Ass);
        mListView.setAdapter(mAdapter);
        mListView.setClickable(true);

        mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {

                textView.setText(Ass[arg2]);

        });

    }

Here is the XML FILE

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.a21.proplay.MainActivity">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/ass"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginBottom="67dp" />

    <TextView
        android:text="TextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginLeft="20dp"
        android:layout_marginStart="20dp"
        android:layout_marginBottom="23dp"
        android:id="@+id/textView" />
</RelativeLayout>

When I click to list it crashes.I cannot figure out why the click is not working.How can I fix that?

1

nice variables naming – Anton Kazakov May 26 '17 at 19:11

score 2 · Accepted Answer · answered May 26 '17 at 18:40

2

add this line

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

answered May 26 '17 at 18:40

Solaiman Hossain

475
2
8

score 1 · Answer 2 · answered May 26 '17 at 18:40

Your textView is null.

initialize it like:

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

change your code to :

mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {

            String selectedFromList =(String) (mListView.getItemAtPosition(arg2));
            textView.setText(selectedFromList);

    });

Android Listview Click crashes

2 Answers2