使用listpreference并获取密钥有效，但没有确定按钮

Question

I'm using listpreference in my android app and getting my key values and all is well and works good (now that you guys have helped me) BUT - when my listpreference menus popup, they only contain a cancel button.

Let's say the user is choosing between red, blue, and green. When the listpreference dialog first pops-up, the dialog only shows a cancel button. Because of that, the dialog disappears as soon as the user selects their choice. I would like it so that when the user chooses their setting, they see the radio button get highlighted and then they go ahead and click the ok button...but I don't have an ok button and can't figure out why. Any help would be awesome...al

Answer 1

I have done what the previous answer suggested and implemented my own ListPreference based on Android source code. Below is my implementation that adds the OK button.

myPreferenceList.java

import android.app.AlertDialog.Builder;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.preference.ListPreference;
import android.util.AttributeSet;


public class myPreferenceList extends ListPreference implements OnClickListener{

    private int mClickedDialogEntryIndex;

    public myPreferenceList(Context context, AttributeSet attrs) {
        super(context, attrs);


    }

    public myPreferenceList(Context context) {
        this(context, null);
    }

    private int getValueIndex() {
        return findIndexOfValue(this.getValue() +"");
    }


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

        mClickedDialogEntryIndex = getValueIndex();
        builder.setSingleChoiceItems(this.getEntries(), mClickedDialogEntryIndex, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                mClickedDialogEntryIndex = which;

            }
        });

        System.out.println(getEntry() + " " + this.getEntries()[0]);
        builder.setPositiveButton("OK", this);
    }

    public  void onClick (DialogInterface dialog, int which)
    {
        this.setValue(this.getEntryValues()[mClickedDialogEntryIndex]+"");
    }

}

Then you can use the class in your preference.xml as follow:

<com.yourApplicationName.myPreferenceList
            android:key="yourKey"
            android:entries="@array/yourEntries"
            android:entryValues="@array/yourValues"
            android:title="@string/yourTitle" />

Answer 2

You can clone and reimplement ListPreference to work the way you want, making your own custom Preference class as a result.

However, ListPreference is set up to only use a negative ("Cancel") button. As the source code says:

    /*
     * The typical interaction for list-based dialogs is to have
     * click-on-an-item dismiss the dialog instead of the user having to
     * press 'Ok'.
     */

Answer 3

The code by techi50 is correct, but does not work for 'cancel button'. Here are some modification:

protected void onPrepareDialogBuilder(Builder builder) {
    super.onPrepareDialogBuilder(builder);

     prevDialogEntryIndex = getValueIndex();       // add this
     mClickedDialogEntryIndex = getValueIndex();
     builder.setSingleChoiceItems(this.getEntries(), mClickedDialogEntryIndex, new DialogInterface.OnClickListener() {
     public void onClick(DialogInterface dialog, int which) {
            mClickedDialogEntryIndex = which;

        }
    });

    builder.setPositiveButton("OK", this);
}

public  void onClick (DialogInterface dialog, int which)
{
// when u click Cancel: which = -2; 
// when u click     OK: which = -1; 

    if(which == -2){
      this.setValue(this.getEntryValues()[prevDialogEntryIndex]+"");
    }
    else {
      this.setValue(this.getEntryValues()[mClickedDialogEntryIndex]+"");
    }
}

Answer 4

The solution proposed by Techi50 and ajinkya works ok. However, if you also have the OnPreferenceChangeListener it won't fire.

    yourListPreference.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
                    @Override
                    public boolean onPreferenceChange(Preference preference, Object o) {

                       //Won't get there

                        preference.setSummary(o.toString());
                        return true;
                    }
                });

To fix this you need to invoke the callChangeListener() function on OK button click, like this:

 public  void onClick (DialogInterface dialog, int which) {
        if(which == -2) {
            this.setValue(this.getEntryValues()[mClickedDialogEntryIndexPrev]+"");
        }
        else {
            String value = this.getEntryValues()[mClickedDialogEntryIndex] + "";
            this.setValue(value);
            callChangeListener(value);
        }
    }