Question

I’d like to create an application for tablets using 2 panels. The left one as a menu and the right one as a content presenter. In fact the behavior I expect is similar to the one in Gmail app.

I’m currently using 2 fragments. One is basically a ListView with room names plus some buttons. The other one (the content) includes some information about the selected room.

The room I select in the left panel should stay highlighted – like in the Gmail app. I was trying for many hours to achieve this effect using selectors, but failed.

Moreover I found 2 different opinions about this approach..

1) “Do not try to keep the focus or selection in touch mode”

2) “In general, use the pane on the right to present more information about the item you selected in the left pane. Make sure to keep the item in the left pane selected in order to establish the relationship between the panels.”

Can you tell me how to achieve this (just to keep the selected item distinguished from the rest)?
Maybe a ListView isn’t the best approach here?

UPDATE

Thanks to Christoph Eberhardt’s answer I created a sample project that works fine. It’s available on github.

Answer 1

Create an xml file in res/drawable/list_item_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_selected="true" android:drawable="@drawable/list_pressed" />
    <item android:drawable="@drawable/list_default" />
</selector>

For the list elements make an own xml file res/layout/list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/text1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:gravity="center_vertical"
    android:minHeight="?android:attr/listPreferredItemHeight"
    android:paddingLeft="20dp"
    android:background="@drawable/list_item_selector"
/>

Then when creating the list adapter do:

setListAdapter(new CustomAdapter<String>(getActivity(),
            R.layout.list_item, stringArray));

Now all you have to do is providing the drawables list_default and list_pressed and list_altered

The CustomAdpater looks like:

package com.test.listview_keep_selected;

import android.app.Activity;
import android.content.Context;
import android.graphics.drawable.StateListDrawable;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class CustomAdapter<T> extends ArrayAdapter<T> {

    private Context m_cContext;

    public CustomAdapter(Context context, int textViewResourceId,
            T[] objects) {

        super(context, textViewResourceId, objects);
        this.m_cContext = context;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        final View returnView = super.getView(position, convertView, parent);
        final ListView listView  = (ListView) ((Activity) m_cContext).findViewById(R.id.listViewTest);
        returnView.setOnClickListener(new OnClickListener(
                ) {


            @Override
            public void onClick(View v) {
                for(int i = 0; i< listView.getChildCount(); i++)
                    listView.getChildAt(i).setSelected(false);
                StateListDrawable states = new StateListDrawable();
                states.addState(new int[] {android.R.attr.state_selected},
                        m_cContext.getResources().getDrawable(R.drawable.list_pressed));
                states.addState(new int[] { },
                        m_cContext.getResources().getDrawable(R.drawable.list_altered));
                v.setBackgroundDrawable(states);
                v.setSelected(true);
            }
        });
        return returnView;
    }

}

Edit:

And if you don’t have it already:

listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);

Edit:
Don’t set the choice mode with a plain ListView, only makes sense if you have e.g. a ListFragment as I have in my code

It’s not perfect now, but from now on you should be fine after playing around a bit.

What also might help is: ListView item background via custom selector

Edit:

Now it should work as you want it^^