Java tutorial
/* * Copyright (C) 2010 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package android.preference; import android.annotation.ArrayRes; import android.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; import java.util.HashSet; import java.util.Set; /** * A {@link Preference} that displays a list of entries as * a dialog. * <p> * This preference will store a set of strings into the SharedPreferences. * This set will contain one or more values from the * {@link #setEntryValues(CharSequence[])} array. * * @attr ref android.R.styleable#MultiSelectListPreference_entries * @attr ref android.R.styleable#MultiSelectListPreference_entryValues */ public class MultiSelectListPreference extends DialogPreference { private CharSequence[] mEntries; private CharSequence[] mEntryValues; private Set<String> mValues = new HashSet<String>(); private Set<String> mNewValues = new HashSet<String>(); private boolean mPreferenceChanged; public MultiSelectListPreference(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); final TypedArray a = context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.MultiSelectListPreference, defStyleAttr, defStyleRes); mEntries = a.getTextArray(com.android.internal.R.styleable.MultiSelectListPreference_entries); mEntryValues = a.getTextArray(com.android.internal.R.styleable.MultiSelectListPreference_entryValues); a.recycle(); } public MultiSelectListPreference(Context context, AttributeSet attrs, int defStyleAttr) { this(context, attrs, defStyleAttr, 0); } public MultiSelectListPreference(Context context, AttributeSet attrs) { this(context, attrs, com.android.internal.R.attr.dialogPreferenceStyle); } public MultiSelectListPreference(Context context) { this(context, null); } /** * Sets the human-readable entries to be shown in the list. This will be * shown in subsequent dialogs. * <p> * Each entry must have a corresponding index in * {@link #setEntryValues(CharSequence[])}. * * @param entries The entries. * @see #setEntryValues(CharSequence[]) */ public void setEntries(CharSequence[] entries) { mEntries = entries; } /** * @see #setEntries(CharSequence[]) * @param entriesResId The entries array as a resource. */ public void setEntries(@ArrayRes int entriesResId) { setEntries(getContext().getResources().getTextArray(entriesResId)); } /** * The list of entries to be shown in the list in subsequent dialogs. * * @return The list as an array. */ public CharSequence[] getEntries() { return mEntries; } /** * The array to find the value to save for a preference when an entry from * entries is selected. If a user clicks on the second item in entries, the * second item in this array will be saved to the preference. * * @param entryValues The array to be used as values to save for the preference. */ public void setEntryValues(CharSequence[] entryValues) { mEntryValues = entryValues; } /** * @see #setEntryValues(CharSequence[]) * @param entryValuesResId The entry values array as a resource. */ public void setEntryValues(@ArrayRes int entryValuesResId) { setEntryValues(getContext().getResources().getTextArray(entryValuesResId)); } /** * Returns the array of values to be saved for the preference. * * @return The array of values. */ public CharSequence[] getEntryValues() { return mEntryValues; } /** * Sets the value of the key. This should contain entries in * {@link #getEntryValues()}. * * @param values The values to set for the key. */ public void setValues(Set<String> values) { mValues.clear(); mValues.addAll(values); persistStringSet(values); } /** * Retrieves the current value of the key. */ public Set<String> getValues() { return mValues; } /** * Returns the index of the given value (in the entry values array). * * @param value The value whose index should be returned. * @return The index of the value, or -1 if not found. */ 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; } @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() { 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); } 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; } @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 int valueCount = defaultValues.length; final Set<String> result = new HashSet<String>(); for (int i = 0; i < valueCount; i++) { result.add(defaultValues[i].toString()); } return result; } @Override protected void onSetInitialValue(boolean restoreValue, Object defaultValue) { setValues(restoreValue ? getPersistedStringSet(mValues) : (Set<String>) defaultValue); } @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 = getValues(); return myState; } private static class SavedState extends BaseSavedState { Set<String> values; public SavedState(Parcel source) { super(source); values = new HashSet<String>(); String[] strings = source.readStringArray(); final int stringCount = strings.length; for (int i = 0; i < stringCount; i++) { values.add(strings[i]); } } public SavedState(Parcelable superState) { super(superState); } @Override public void writeToParcel(Parcel dest, int flags) { super.writeToParcel(dest, flags); dest.writeStringArray(values.toArray(new String[0])); } public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() { public SavedState createFromParcel(Parcel in) { return new SavedState(in); } public SavedState[] newArray(int size) { return new SavedState[size]; } }; } }