ListView onItemClickListener

Question

An error:

09-26 13:09:38.551: E/AndroidRuntime(25966): FATAL EXCEPTION: main
09-26 13:09:38.551: E/AndroidRuntime(25966): java.lang.ClassCastException: java.util.HashMap
09-26 13:09:38.551: E/AndroidRuntime(25966):    at com.example.customlayoutlistview.MainActivity$1.onItemClick(MainActivity.java:79)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at android.widget.AdapterView.performItemClick(AdapterView.java:284)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at android.widget.ListView.performItemClick(ListView.java:3584)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at android.widget.AbsListView$PerformClick.run(AbsListView.java:1846)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at android.os.Handler.handleCallback(Handler.java:587)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at android.os.Handler.dispatchMessage(Handler.java:92)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at android.os.Looper.loop(Looper.java:130)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at android.app.ActivityThread.main(ActivityThread.java:3687)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at java.lang.reflect.Method.invokeNative(Native Method)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at java.lang.reflect.Method.invoke(Method.java:507)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
09-26 13:09:38.551: E/AndroidRuntime(25966):    at dalvik.system.NativeStart.main(Native Method)

is being found on the following method implementation:

listView.setOnItemClickListener(new OnItemClickListener() {

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position,
            long id) {
        // TODO Auto-generated method stub
        int itemPostition = position;
        String itemString = (String)parent.getItemAtPosition(position);
        Toast.makeText(getApplicationContext(), ""+itemPostition+" "+itemString, Toast.LENGTH_SHORT).show();
    }
});

Line 79:

String itemString = (String)parent.getItemAtPosition(position);

The java class:

public class MainActivity extends Activity {

    ArrayList<HashMap<String, Object>> listFill;
    ListView listView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listFill = new ArrayList<HashMap<String, Object>>();
        listView = (ListView) findViewById(R.id.listofviews);

        // Initializing and defining the contents to be filled
        int[] songIcons = { R.drawable.music, R.drawable.music,
                R.drawable.music, R.drawable.music, R.drawable.music };
        String[] songTitle = { "Song One", "Song Two", "Song Three",
                "Song Four", "Song Five" };
        String[] songDescription = { "Description One", "Description Two",
                "Description Three", "Description Four", "Description Five" };

        //Looping through the contents and adding it to our ArrayList 
        for (int i = 0; i < songIcons.length; i++) {
            HashMap<String, Object> toFill = new HashMap<String, Object>();
            //Filling the HashMap first
            toFill.put("songIcon", songIcons[i]);
            toFill.put("songTitle", songTitle[i]);
            toFill.put("songDescription", songDescription[i]);
            //Filling the HashMap inside the ArrayList
            listFill.add(toFill);
        }

        //Creating adapter for the listView
        ListAdapter adapter = new SimpleAdapter(MainActivity.this, listFill,
                R.layout.custom_layout, new String[] { "songIcon", "songTitle",
                        "songDescription" }, new int[] { R.id.list_icon,
                        R.id.list_title, R.id.list_description });
        listView.setAdapter(adapter);
//      setListAdapter(adapter);

        //Implementing on itemClicked

        listView.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position,
                    long id) {
                // TODO Auto-generated method stub
                int itemPostition = position;
                String itemString = (String)parent.getItemAtPosition(position);
                Toast.makeText(getApplicationContext(), ""+itemPostition+" "+itemString, Toast.LENGTH_SHORT).show();
            }
        });

    }

Why am I getting this error ? Can someone please help. I am trying to get the item contents on listView click

Answer 1

您正在将HashMap对象转换为String对象，这会导致此异常

Answer 2

here:

String itemString = (String)parent.getItemAtPosition(position);

what is returned is an HashMap and you're casting it to a String.

Answer 3

try this

String i= String.valueOf(position);
Toast.makeText(getApplicationContext(), i, Toast.LENGTH_LONG).show();

Answer 4

As ArrayList listFill is passed to adapter of your ListView, you can get an HashMap Object containing title, icon and description for the song corresponding to the position of item which is clicked. Thus,

HashMap<String, Object> itemSong = HashMap<String, Object>parent.getItemAtPosition(position);
String itemString = itemSong.get("SongTitle"); 

will meet your requirements.

Answer 5

try this

String itemString = parent.getItemAtPosition(position).toString();
Toast.makeText(getApplicationContext(), ""+itemPostition+" "+itemString, Toast.LENGTH_SHORT).show();