MultiSelectListPreference.java

package org.holoeverywhere.preference;

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

import org.holoeverywhere.app.AlertDialog.Builder;

import android.content.Context;
import android.content.DialogInterface;
import android.content.res.TypedArray;
import android.os.Parcel;
import android.os.Parcelable;
import android.util.AttributeSet;

public class MultiSelectListPreference extends DialogPreference {
    private static class SavedState extends BaseSavedState {
        Set<String> values;

        public SavedState(Parcel source) {
            super(source);
            String[] v = source.createStringArray();
            values = new HashSet<String>(Arrays.asList(v));
        }

        public SavedState(Parcelable superState) {
            super(superState);
        }

        @Override
        public void writeToParcel(Parcel dest, int flags) {
            super.writeToParcel(dest, flags);
            dest.writeStringArray(values.toArray(new String[values.size()]));
        }
    }

    private CharSequence[] mEntries;
    private CharSequence[] mEntryValues;
    private Set<String> mNewValues = new HashSet<String>();
    private boolean mPreferenceChanged;

    private Set<String> mValues = new HashSet<String>();

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

    public MultiSelectListPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
        context = getContext();
        TypedArray a = context.obtainStyledAttributes(attrs,
                R.styleable.ListPreference, 0, 0);
        mEntries = a.getTextArray(R.styleable.ListPreference_entries);
        mEntryValues = a.getTextArray(R.styleable.ListPreference_entryValues);
        a.recycle();
    }

    public int findIndexOfValue(String value) {
        if (value != null && mEntryValues != null) {
            for (int i = mEntryValues.length - 1; i >= 0; i--) {
                if (mEntryValues[i].equals(value)) {
                    return i;
                }
            }
        }
        return -1;
    }

    public CharSequence[] getEntries() {
        return mEntries;
    }

    public CharSequence[] getEntryValues() {
        return mEntryValues;
    }

    private boolean[] getSelectedItems() {
        final CharSequence[] entries = mEntryValues;
        final int entryCount = entries.length;
        final Set<String> values = mValues;
        boolean[] result = new boolean[entryCount];

        for (int i = 0; i < entryCount; i++) {
            result[i] = values.contains(entries[i].toString());
        }

        return result;
    }

    public Set<String> getValues() {
        return mValues;
    }

    @Override
    protected void onDialogClosed(boolean positiveResult) {
        super.onDialogClosed(positiveResult);

        if (positiveResult && mPreferenceChanged) {
            final Set<String> values = mNewValues;
            if (callChangeListener(values)) {
                setValues(values);
            }
        }
        mPreferenceChanged = false;
    }

    @Override
    protected Object onGetDefaultValue(TypedArray a, int index) {
        final CharSequence[] defaultValues = a.getTextArray(index);
        final Set<String> result = new HashSet<String>();
        if (defaultValues != null) {
            for (CharSequence s : defaultValues) {
                result.add(s.toString());
            }
        }
        return result;
    }

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

        if (mEntries == null || mEntryValues == null) {
            throw new IllegalStateException(
                    "MultiSelectListPreference requires an entries array and "
                            + "an entryValues array.");
        }

        boolean[] checkedItems = getSelectedItems();
        builder.setMultiChoiceItems(mEntries, checkedItems,
                new DialogInterface.OnMultiChoiceClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which,
                            boolean isChecked) {
                        if (isChecked) {
                            mPreferenceChanged |= mNewValues
                                    .add(mEntryValues[which].toString());
                        } else {
                            mPreferenceChanged |= mNewValues
                                    .remove(mEntryValues[which].toString());
                        }
                    }
                });
        mNewValues.clear();
        mNewValues.addAll(mValues);
    }

    @Override
    protected Parcelable onSaveInstanceState() {
        final Parcelable superState = super.onSaveInstanceState();
        if (isPersistent()) {
            // No need to save instance state
            return superState;
        }

        final SavedState myState = new SavedState(superState);
        myState.values = new HashSet<String>(getValues());
        return myState;
    }

    @SuppressWarnings("unchecked")
    @Override
    protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
        setValues(restoreValue ? getPersistedStringSet(mValues)
                : (Set<String>) defaultValue);
    }

    public void setEntries(CharSequence[] entries) {
        mEntries = entries;
    }

    public void setEntries(int entriesResId) {
        setEntries(getContext().getResources().getTextArray(entriesResId));
    }

    public void setEntryValues(CharSequence[] entryValues) {
        mEntryValues = entryValues;
    }

    public void setEntryValues(int entryValuesResId) {
        setEntryValues(getContext().getResources().getTextArray(
                entryValuesResId));
    }

    public void setValues(Set<String> values) {
        mValues.clear();
        mValues.addAll(values);

        persistStringSet(values);
    }
}