Java tutorial
/* * Copyright (C) 2015 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.support.v7.preference; import android.content.Context; import android.content.res.TypedArray; import android.os.Parcel; import android.os.Parcelable; import android.support.annotation.ArrayRes; import android.support.annotation.NonNull; import android.support.v4.content.res.TypedArrayUtils; import android.support.v7.preference.internal.AbstractMultiSelectListPreference; import android.util.AttributeSet; import java.util.Collections; 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 name android:entries * @attr name android:entryValues */ public class MultiSelectListPreference extends AbstractMultiSelectListPreference { private CharSequence[] mEntries; private CharSequence[] mEntryValues; private Set<String> mValues = new HashSet<>(); public MultiSelectListPreference(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.MultiSelectListPreference, defStyleAttr, defStyleRes); mEntries = TypedArrayUtils.getTextArray(a, R.styleable.MultiSelectListPreference_entries, R.styleable.MultiSelectListPreference_android_entries); mEntryValues = TypedArrayUtils.getTextArray(a, R.styleable.MultiSelectListPreference_entryValues, R.styleable.MultiSelectListPreference_android_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, TypedArrayUtils.getAttr(context, R.attr.dialogPreferenceStyle, android.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; } protected 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 Object onGetDefaultValue(TypedArray a, int index) { final CharSequence[] defaultValues = a.getTextArray(index); final Set<String> result = new HashSet<>(); for (final CharSequence defaultValue : defaultValues) { result.add(defaultValue.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; } @Override protected void onRestoreInstanceState(Parcelable state) { if (state == null || !state.getClass().equals(SavedState.class)) { // Didn't save state for us in onSaveInstanceState super.onRestoreInstanceState(state); return; } SavedState myState = (SavedState) state; super.onRestoreInstanceState(myState.getSuperState()); setValues(myState.values); } private static class SavedState extends BaseSavedState { Set<String> values; public SavedState(Parcel source) { super(source); final int size = source.readInt(); values = new HashSet<>(); String[] strings = new String[size]; source.readStringArray(strings); Collections.addAll(values, strings); } public SavedState(Parcelable superState) { super(superState); } @Override public void writeToParcel(@NonNull Parcel dest, int flags) { super.writeToParcel(dest, flags); dest.writeInt(values.size()); dest.writeStringArray(values.toArray(new String[values.size()])); } public static final Creator<SavedState> CREATOR = new Creator<SavedState>() { public SavedState createFromParcel(Parcel in) { return new SavedState(in); } public SavedState[] newArray(int size) { return new SavedState[size]; } }; } }