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custom row in a listPreference?

开发者 https://www.devze.com 2023-02-01 18:55 出处：网络
I am trying to create a ListPreference but somehow disable one of the items. Sort of like gray it out or something and not have the ability to choose it. It will be an upcoming feature and I want it t
相关专题：androidlistadapterlistpreference

I am trying to create a ListPreference but somehow disable one of the items. Sort of like gray it out or something and not have the ability to choose it. It will be an upcoming feature and I want it to be开发者_如何学编程 in the list just not selectable.

I have created a custom ListPreference class and in that class a custom adapter, hoping to use the adapter to create what I want.

The code works, and it sets the adapter, but none of the adapter functions get called. I set breakpoints on the methods, such as getCount() but they never get called.

Here's my code. Custom ListPreference taken from http://blog.350nice.com/wp/archives/240

import android.content.Context;
import android.content.DialogInterface;
import android.graphics.Color;
import android.preference.ListPreference;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.app.AlertDialog.Builder;

public class CustomListPreference extends ListPreference {

    private boolean[] mClickedDialogEntryIndices;
    CustomListPreferenceAdapter customListPreferenceAdapter = null;
    Context mContext;

    public CustomListPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
        mContext = context;
        mClickedDialogEntryIndices = new boolean[getEntries().length];
    }

    @Override
    protected void onPrepareDialogBuilder(Builder builder) {
        CharSequence[] entries = getEntries();
        CharSequence[] entryValues = getEntryValues();
        if (entries == null || entryValues == null
                || entries.length != entryValues.length) {
            throw new IllegalStateException(
                    "ListPreference requires an entries array "
                    +"and an entryValues array which are both the same length");
        }
        builder.setMultiChoiceItems(entries, mClickedDialogEntryIndices,
                new DialogInterface.OnMultiChoiceClickListener() {

                    public void onClick(DialogInterface dialog, int which,
                            boolean val) {
                        mClickedDialogEntryIndices[which] = val;
                    }
                });
        // setting my custom list adapter
        customListPreferenceAdapter = new CustomListPreferenceAdapter(mContext);
        builder.setAdapter(customListPreferenceAdapter, null);
    }

    private class CustomListPreferenceAdapter extends BaseAdapter {

        public CustomListPreferenceAdapter(Context context) {}

        public int getCount() {
            return 1;
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            convertView.setBackgroundColor(Color.BLUE);
            return convertView;
        }
    }
}

OK I got this to work, mostly. I had to use a custom defined class that extends ListPreference. Then inside of that I had to create a custom adapter class just like you would for a ListView and set it to the builder using builder.setAdapter(). I also had to define listeners for both the RadioButtons and the ListView rows that handled unchecking of the RadioButtons and such. The only issues I still have are, my custom ListPreference has both an OK and a Cancel button where a ListPreference only has the cancel button. I don't know how to remove the OK button. Also, I can't get the rows to highlight when I click on them like they do in a regular ListPreference.

The java code for the custom ListPreference class. Be sure to mind things like your package name, the preference name (key), your entries and values for the ListPreference, and the names of your xml items.

package your.package.here;

import java.util.ArrayList;
import android.content.Context;
import android.content.DialogInterface;
import android.content.SharedPreferences;
import android.graphics.Color;
import android.preference.ListPreference;
import android.preference.PreferenceManager;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CompoundButton;
import android.widget.RadioButton;
import android.widget.TextView;
import android.app.Dialog;
import android.app.AlertDialog.Builder;

public class CustomListPreference extends ListPreference
{   
    CustomListPreferenceAdapter customListPreferenceAdapter = null;
    Context mContext;
    private LayoutInflater mInflater;
    CharSequence[] entries;
    CharSequence[] entryValues;
    ArrayList<RadioButton> rButtonList;
    SharedPreferences prefs;
    SharedPreferences.Editor editor;

    public CustomListPreference(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        mContext = context;
        mInflater = LayoutInflater.from(context);
        rButtonList = new ArrayList<RadioButton>();
        prefs = PreferenceManager.getDefaultSharedPreferences(mContext);
        editor = prefs.edit();
    }

    @Override
    protected void onPrepareDialogBuilder(Builder builder)
    {
        entries = getEntries();
        entryValues = getEntryValues();

        if (entries == null || entryValues == null || entries.length != entryValues.length )
        {
            throw new IllegalStateException(
                    "ListPreference requires an entries array and an entryValues array which are both the same length");
        }

        customListPreferenceAdapter = new CustomListPreferenceAdapter(mContext);

        builder.setAdapter(customListPreferenceAdapter, new DialogInterface.OnClickListener()
        {
            public void onClick(DialogInterface dialog, int which)
            {

            }
        });
    }

    private class CustomListPreferenceAdapter extends BaseAdapter
    {        
        public CustomListPreferenceAdapter(Context context)
        {

        }

        public int getCount()
        {
            return entries.length;
        }

        public Object getItem(int position)
        {
            return position;
        }

        public long getItemId(int position)
        {
            return position;
        }

        public View getView(final int position, View convertView, ViewGroup parent)
        {  
            View row = convertView;
            CustomHolder holder = null;

            if(row == null)
            {                                                                   
                row = mInflater.inflate(R.layout.custom_list_preference_row, parent, false);
                holder = new CustomHolder(row, position);
                row.setTag(holder);

                // do whatever you need here, for me I wanted the last item to be greyed out and unclickable
                if(position != 3)
                {
                    row.setClickable(true);
                    row.setOnClickListener(new View.OnClickListener()
                    {
                        public void onClick(View v)
                        {
                            for(RadioButton rb : rButtonList)
                            {
                                if(rb.getId() != position)
                                    rb.setChecked(false);
                            }

                            int index = position;
                            int value = Integer.valueOf((String) entryValues[index]);
                            editor.putInt("yourPref", value);

                            Dialog mDialog = getDialog();
                            mDialog.dismiss();
                        }
                    });
                }
            }

            return row;
        }

        class CustomHolder
        {
            private TextView text = null;
            private RadioButton rButton = null;

            CustomHolder(View row, int position)
            {    
                text = (TextView)row.findViewById(R.id.custom_list_view_row_text_view);
                text.setText(entries[position]);
                rButton = (RadioButton)row.findViewById(R.id.custom_list_view_row_radio_button);
                rButton.setId(position);

                // again do whatever you need to, for me I wanted this item to be greyed out and unclickable
                if(position == 3)
                {
                    text.setTextColor(Color.LTGRAY);
                    rButton.setClickable(false);
                }

                // also need to do something to check your preference and set the right button as checked

                rButtonList.add(rButton);
                rButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener()
                {
                    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked)
                    {
                        if(isChecked)
                        {
                            for(RadioButton rb : rButtonList)
                            {
                                if(rb != buttonView)
                                    rb.setChecked(false);
                            }

                            int index = buttonView.getId();
                            int value = Integer.valueOf((String) entryValues[index]);
                            editor.putInt("yourPref", value);

                            Dialog mDialog = getDialog();
                            mDialog.dismiss();
                        }
                    }
                });
            }
        }
    }
}

The xml for my PreferenceActivity. This is not my full xml, took out all my other preference items for simplicity. Again, be sure to mind the package name, the custom ListPreference class must be referenced by the package name. Also mind the names of the preference and the array names that hold the entries and values.

<?xml version="1.0" encoding="utf-8"?>

<PreferenceScreen
    xmlns:android="http://schemas.android.com/apk/res/android">

        <PreferenceCategory
                android:title="Your Title">

                <your.package.here.CustomListPreference
                    android:key="yourPref"
                    android:title="Your Title"
                    android:dialogTitle="Your Title"
                    android:summary="Your Summary"
                    android:defaultValue="1"
                    android:entries="@array/yourArray"
                    android:entryValues="@array/yourValues"/>

        </PreferenceCategory>
</PreferenceScreen>

My xml for the dialog's list view row. In the getView method be sure to use the name of this xml file in the line that inflates this.

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:paddingBottom="8dip"
    android:paddingTop="8dip"
    android:paddingLeft="10dip"
    android:paddingRight="10dip">

    <TableLayout
        android:id="@+id/custom_list_view_row_table_layout"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:stretchColumns="0">

        <TableRow
            android:id="@+id/custom_list_view_row_table_row"
            android:gravity="center_vertical"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">

            <TextView
                android:id="@+id/custom_list_view_row_text_view"
                android:textSize="22sp"
                android:textColor="#000000"  
                android:gravity="center_vertical"
                android:layout_width="160dip" 
                android:layout_height="40dip" />

            <RadioButton
                android:checked="false"
                android:id="@+id/custom_list_view_row_radio_button"/>
        </TableRow>
    </TableLayout>

</LinearLayout>

Finally, under res/values here is my array.xml that contains the entry names and values for the ListPreference. Again, shortened mine for simplicity.

<?xml version="1.0" encoding="utf-8"?>
<resources> 
    <string-array name="yourArray">
        <item>Item 1</item>
        <item>Item 2</item>
        <item>Item 3</item>
        <item>Item 4</item>
    </string-array>

    <string-array name="yourValues">
        <item>0</item>
        <item>1</item>
        <item>2</item>
        <item>3</item>
    </string-array>
</resources>

This worked well for me. I used an Adapter approach that injects a wrapped adapter into the view.

Here is the base wrapped adapter class:

import android.database.DataSetObserver;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListAdapter;
import android.widget.WrapperListAdapter;

class ListPrefWrapperAdapter implements WrapperListAdapter {
    private ListAdapter mOrigAdapter;

    public ListPrefWrapperAdapter(ListAdapter origAdapter) {
        mOrigAdapter = origAdapter;
    }

    @Override
    public ListAdapter getWrappedAdapter() {
        return mOrigAdapter;
    }

    @Override
    public boolean areAllItemsEnabled() {
        return getWrappedAdapter().areAllItemsEnabled();
    }

    @Override
    public boolean isEnabled(int position) {
        return getWrappedAdapter().isEnabled(position);
    }

    @Override
    public void registerDataSetObserver(DataSetObserver observer) {
        getWrappedAdapter().registerDataSetObserver(observer);
    }

    @Override
    public void unregisterDataSetObserver(DataSetObserver observer) {
        getWrappedAdapter().unregisterDataSetObserver(observer);
    }

    @Override
    public int getCount() {
        return getWrappedAdapter().getCount();
    }

    @Override
    public Object getItem(int position) {
        return getWrappedAdapter().getItem(position);
    }

    @Override
    public long getItemId(int position) {
        return getWrappedAdapter().getItemId(position);
    }

    @Override
    public boolean hasStableIds() {
        return getWrappedAdapter().hasStableIds();
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        return getWrappedAdapter().getView(position, convertView, parent);
    }

    @Override
    public int getItemViewType(int position) {
        return getWrappedAdapter().getItemViewType(position);
    }

    @Override
    public int getViewTypeCount() {
        return getWrappedAdapter().getViewTypeCount();
    }

    @Override
    public boolean isEmpty() {
        return getWrappedAdapter().isEmpty();
    }
}

Here is the CustomListPreference base class that uses the ListPrefWrapperAdapter:

import android.app.AlertDialog;
import android.content.Context;
import android.os.Bundle;
import android.util.AttributeSet;
import android.widget.ListAdapter;
import android.widget.ListView;

public class CustomListPreference extends ListPreference {
    public CustomListPreference(Context context) {
        super(context);
    }

    public CustomListPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void showDialog(Bundle state) {
        super.showDialog(state);
        AlertDialog dialog = (AlertDialog) getDialog();
        ListView listView = dialog.getListView();
        ListAdapter adapter = listView.getAdapter();
        final ListPrefWrapperAdapter fontTypeAdapter = createWrapperAdapter(adapter);

        // Adjust the selection because resetting the adapter loses the selection.
        int selectedPosition = findIndexOfValue(getValue());
        listView.setAdapter(fontTypeAdapter);
        if (selectedPosition != -1) {
            listView.setItemChecked(selectedPosition, true);
            listView.setSelection(selectedPosition);
        }
    }

    protected ListPrefWrapperAdapter createWrapperAdapter(ListAdapter origAdapter) {
        return new ListPrefWrapperAdapter(origAdapter);
    }

}

Finally, here are the derived classes that do the disabling and enabling of specific rows:

import android.content.Context;
import android.graphics.Color;
import android.graphics.Typeface;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CheckedTextView;
import android.widget.ListAdapter;

public class FontTypePreference extends CustomListPreference {

    public FontTypePreference(Context context) {
        super(context);
    }

    public FontTypePreference(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected ListPrefWrapperAdapter createWrapperAdapter(ListAdapter origAdapter) {
        return new Adapter(origAdapter);
    }

    private class Adapter extends ListPrefWrapperAdapter {
        private static final float TEXT_SIZE = 25.0f;
        private static final int STARTING_UPGRADE_REQUIRED_INDEX = 8;

        public Adapter(ListAdapter origAdapter) {
            super(origAdapter);
        }

        @Override
        public boolean areAllItemsEnabled() {
            return false;
        }

        @Override
        public boolean isEnabled(int position) {
            return position < STARTING_UPGRADE_REQUIRED_INDEX;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            CheckedTextView textView = (CheckedTextView) getWrappedAdapter()
                    .getView(position, convertView, parent);
            textView.setTextColor(position < STARTING_UPGRADE_REQUIRED_INDEX ?
                    Color.BLACK : Color.RED);
            return textView;
        }


    }

}

I have only tested this code on SDK version 15 and above.

Probably have to add editor.commit(); after each editor.putInt(...)

function getcount() returns is wrong.

public int getCount()
    {
        return entries.length;
    }

    public Object getItem(int position)
    {
        return null;
    }

    public long getItemId(int position)
    {
        return position;
    }

Thanks Bob for that answer, and Vamsi for trying to correct the duplicate entries bug, but Vamsi's fix didn't work for me. I had to keep an array of views and return it on the position if it had already been created before. So here is my full CustomListPreferenceAdapter class. It also contains the fix to check the selected preference value.

private class CustomListPreferenceAdapter extends BaseAdapter
{
    View[] Views;

    public CustomListPreferenceAdapter(Context context)
    {
        Views = new View[entries.length];
    }

    public int getCount()
    {
        return entries.length;
    }

    public Object getItem(int position)
    {
        return null;
    }

    public long getItemId(int position)
    {
        return position;
    }

    public View getView(final int position, View convertView, ViewGroup parent)
    {  
        View row = Views[position];
        CustomHolder holder = null;

        if(row == null)
        {                                                             
            row = mInflater.inflate(R.layout.listrow, parent, false);
            holder = new CustomHolder(row, position);
            row.setTag(holder);
            Views[position] = row;
        }

        return row;
    }

    class CustomHolder
    {
        private TextView text = null;
        private RadioButton rButton = null;

        CustomHolder(View row, int position)
        {    
            text = (TextView)row.findViewById(R.id.custom_list_view_row_text_view);
            text.setText(entries[position]);

            rButton = (RadioButton)row.findViewById(R.id.custom_list_view_row_radio_button);
            rButton.setId(position);

            if(getPersistedString("").compareTo((String)entryValues[position])==0)
                rButton.setChecked(true);

            rButtonList.add(rButton);
        }
    }
}

I think you can achieve exactly what you want by setting the enabled flag of the ListPreference to false:

ListPreference lp = (ListPreference) findPreference("YOUR_KEY");
lp.setEnabled(false);

This grays out the description and makes it not selectable.

modified the code as below - 

if(row == null) {                                                                   
    row = mInflater.inflate(R.layout.custom_list_preference_row, parent, false);
    holder = new CustomHolder(row, position);
} else {
    holder = row.getTag()
}
// update the holder with new Text/Drawables etc.,
row.setTag(holder);
return row;

PS - NidhiGondhia requested for modified code, as in the comments this can not be fit, updating the modified code here.

You can do it more easily.

Steps:

  1. Extend ListPreference

    public class CustomListPreference extends ListPreference
{
    Context mContext;

    public CustomListPreference(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        mContext = context;
    }
}

  2. Override onPrepareDialogBuilder and replace mBuilder in DialogPreference with ProxyBuilder: 

    @Override
protected void onPrepareDialogBuilder(android.app.AlertDialog.Builder builder){
    super.onPrepareDialogBuilder(builder);

    if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.FROYO) {
        return;
    }

    // Inject Builder Proxy for intercepting of getView.
    try {
        Field privateBuilderField =
            DialogPreference.class.getDeclaredField("mBuilder");
        privateBuilderField.setAccessible(true);

        privateBuilderField.set(this, new ProxyBuilder(mContext, (android.app.AlertDialog.Builder)privateBuilderField.get(this)));
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }
}

  3. Handle getView in ProxyBuilder->AlertDialog->onShow->getListView->Adapter

    private class ProxyBuilder extends android.app.AlertDialog.Builder{

    android.app.AlertDialog.Builder mBuilder;

    private ProxyBuilder(Context context, AlertDialog.Builder builder) {
        super(context);
        mBuilder = builder;
    }


    @TargetApi(Build.VERSION_CODES.FROYO)
    @Override
    public AlertDialog create() {
        AlertDialog alertDialog = mBuilder.create();
        alertDialog.setOnShowListener(new DialogInterface.OnShowListener() {
            @Override
            public void onShow(DialogInterface dialog) {
                ListView listView = ((AlertDialog)dialog).getListView();
                final ListAdapter originalAdapter = listView.getAdapter();

                listView.setAdapter(new ListAdapter(){
                    @Override
                    public int getCount() {
                        return originalAdapter.getCount();
                    }

                    @Override
                    public Object getItem(int id) {
                        return originalAdapter.getItem(id);
                    }

                    @Override
                    public long getItemId(int id) {
                        return originalAdapter.getItemId(id);
                    }

                    @Override
                    public int getItemViewType(int id) {
                        return originalAdapter.getItemViewType(id);
                    }

                    @Override
                    public View getView(int position, View convertView, ViewGroup parent) {
                        View view = originalAdapter.getView(position, convertView, parent);
                        TextView textView = (TextView)view;
                        textView.setTextColor(Color.RED);
                        return view;
                    }

                    @Override
                    public int getViewTypeCount() {
                        return originalAdapter.getViewTypeCount();
                    }

                    @Override
                    public boolean hasStableIds() {
                        return originalAdapter.hasStableIds();
                    }

                    @Override
                    public boolean isEmpty() {
                        return originalAdapter.isEmpty();
                    }

                    @Override
                    public void registerDataSetObserver(DataSetObserver observer) {
                        originalAdapter.registerDataSetObserver(observer);

                    }

                    @Override
                    public void unregisterDataSetObserver(DataSetObserver observer) {
                        originalAdapter.unregisterDataSetObserver(observer);

                    }

                    @Override
                    public boolean areAllItemsEnabled() {
                        return originalAdapter.areAllItemsEnabled();
                    }

                    @Override
                    public boolean isEnabled(int position) {
                        return originalAdapter.isEnabled(position);
                    }

                });
            }
        });
        return alertDialog;
    }
}

This worked for me, but it did not work well if the list does not fit on the screen (and requires scrolling). It took me a loooong time to find the solution (but I finally did).

First the problem: As described here: getView called with wrong position when scrolling fast you will get unpredictable behavior when you use an onclick listener in:

public View getView(final int position, View convertView, ViewGroup parent)

In my case, the onClick event would be stored in memory and would be executed when the user tried to scroll (slightly).

And now the solution: Put the onClick listener in the main class (at least this worked for me):

public class CustomListPreference extends ListPreference {

// Other code (see above)
@Override
protected void onPrepareDialogBuilder(Builder builder)
{
    builder.setPositiveButton(null, null);

    entries = getEntries();
    entryValues = getEntryValues();

    if (entries == null || entryValues == null || entries.length != entryValues.length )
    {
        throw new IllegalStateException("ListPreference requires an entries array and an entryValues array which are both the same length");
    }

    customListPreferenceAdapter = new CustomListPreferenceAdapter(mContext);

    builder.setAdapter(customListPreferenceAdapter, new DialogInterface.OnClickListener()
    {
        public void onClick(DialogInterface dialog, int position)
        {
            // Code here, using position to indicate the row that was clicked...
            dialog.dismiss();
        }
    });

}

Spend waaaay too much time on this, so hope it will help someone out :)

All in all, still really happy with this code example! (use it as a color picker).

P.S. If you like this post, please vote useful. Thx!

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