Using listpreference and getting the key works but no ok button

问题

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

回答1:

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'.
     */

回答2:

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" />

回答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]+"");
    }
}

回答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);
        }
    }

来源：https://stackoverflow.com/questions/2520021/using-listpreference-and-getting-the-key-works-but-no-ok-button