Question

I have a problem with getting the child’s position of LinearLayout. First I’m adding dynamically a number of buttons and then I’m trying to return each child’s index and display it into a TextView. Here I’m sharing code:

java source:

private String[] categories;

private LinearLayout ll;
private TextView tv;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    categories = getResources().getStringArray(R.array.categories);

    tv = (TextView) findViewById(R.id.text);
    ll = (LinearLayout) findViewById(R.id.hsvLinearLayout);

    for(int i = 0; i < categories.length; i++) {
        Button btn = new Button(this);
        btn.setText(categories[i]);
        btn.setOnClickListener(buttonClick);
        ll.addView(btn);
    }
}

OnClickListener buttonClick = new OnClickListener() {
    public void onClick(View v) {
        tv.setText(ll.indexOfChild(v));
    }
};

xml structure:

<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>

<HorizontalScrollView
    android:id="@+id/Footer"
    android:orientation="horizontal"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:scrollbars="none"
    android:fadingEdge="none"
    >

    <LinearLayout
        android:id="@+id/hsvLinearLayout"
        android:orientation="horizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        >

    </LinearLayout>

</HorizontalScrollView>

<TextView
    android:id="@+id/text"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    />

resources:

<string name="today">Today</string>
<string name="life">Life</string>
<string name="corner">Corner</string>
<string name="banks">Banks</string>
<string name="it">IT</string>
<string name="fun">Fun</string>

<array name="categories">
    <item>@string/today</item>
    <item>@string/life</item>
    <item>@string/corner</item>
    <item>@string/banks</item>
    <item>@string/it</item>
    <item>@string/fun</item>
</array>

The dynamically adding is fine, but the way I’m setting the OnClickListener produce some error. Any help will be useful! The purpose of that is if I want to add one or more button(s) to the HorizontalScrollView not to be necessary to edit many files, and just to go to sting.xml and create a new item into the categories-array!

This is what LogCat produced:

07-12 22:37:17.680: INFO/System.out(331): waiting for debugger to settle...
07-12 22:37:17.900: INFO/System.out(331): debugger has settled (1441)
07-12 22:37:20.870: INFO/ActivityManager(61): Displayed activity com.test/.TestDynam: 10203 ms (total 10203 ms)
07-12 22:37:25.552: WARN/ResourceType(331): No package identifier when getting value for resource number 0x00000000
07-12 22:37:26.871: DEBUG/dalvikvm(132): GC freed 190 objects / 8976 bytes in 901ms

To clarify – the application starts without any errors, but when I click on a button it produces this line from the above log:

07-12 22:37:25.552: WARN/ResourceType(331): No package identifier when getting value for resource number 0x00000000

And this is from debugger:

TestDynam [Android Application] 
    DalvikVM[localhost:8611]    
        Thread [<3> main] (Suspended (exception Resources$NotFoundException))   
            ViewRoot.handleMessage(Message) line: 1704  
            ViewRoot(Handler).dispatchMessage(Message) line: 99 
            Looper.loop() line: 123 
            ActivityThread.main(String[]) line: 4203    
            Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]  
            Method.invoke(Object, Object...) line: 521  
            ZygoteInit$MethodAndArgsCaller.run() line: 791  
            ZygoteInit.main(String[]) line: 549 
            NativeStart.main(String[]) line: not available [native method]  
        Thread [<13> Binder Thread #2] (Running)    
        Thread [<11> Binder Thread #1] (Running)

Answer 1

your problem is resources….
you use the setText(int) method (that index is int…) which looks for resources and not string, this is not StringBuilder for which you can throw any type and get a string.
you needs to replace

tv.setText(ll.indexOfChild(v));

with

tv.setText(Integer.toString(ll.indexOfChild(v)));

and if you want even little bit of efficiency:

public class TestActivity extends Activity {

    private String[] categories;

    private LinearLayout ll;
    private TextView tv;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        categories = getResources().getStringArray(R.array.categories);

        tv = (TextView) findViewById(R.id.text);
        ll = (LinearLayout) findViewById(R.id.hsvLinearLayout);

        for(int i = 0; i < categories.length; i++) {
            Button btn = new Button(this);
            btn.setText(categories[i]);
            btn.setOnClickListener(buttonClick);
            ll.addView(btn);
            int idx = ll.indexOfChild(btn);
            btn.setTag(Integer.toString(idx));
        }
    }

    OnClickListener buttonClick = new OnClickListener() {
        public void onClick(View v) {
            String idxStr = (String)v.getTag();
            tv.setText(idxStr);
        }
    };

}