1 /* 2 * Copyright (C) 2006 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.view; 18 19 import android.os.Parcel; 20 import android.os.Parcelable; 21 22 /** 23 * A {@link Parcelable} implementation that should be used by inheritance 24 * hierarchies to ensure the state of all classes along the chain is saved. 25 */ 26 public abstract class AbsSavedState implements Parcelable { 27 public static final AbsSavedState EMPTY_STATE = new AbsSavedState() {}; 28 29 private final Parcelable mSuperState; 30 31 /** 32 * Constructor used to make the EMPTY_STATE singleton 33 */ AbsSavedState()34 private AbsSavedState() { 35 mSuperState = null; 36 } 37 38 /** 39 * Constructor called by derived classes when creating their SavedState objects 40 * 41 * @param superState The state of the superclass of this view 42 */ AbsSavedState(Parcelable superState)43 protected AbsSavedState(Parcelable superState) { 44 if (superState == null) { 45 throw new IllegalArgumentException("superState must not be null"); 46 } 47 mSuperState = superState != EMPTY_STATE ? superState : null; 48 } 49 50 /** 51 * Constructor used when reading from a parcel. Reads the state of the superclass. 52 * 53 * @param source parcel to read from 54 */ AbsSavedState(Parcel source)55 protected AbsSavedState(Parcel source) { 56 this(source, null); 57 } 58 59 /** 60 * Constructor used when reading from a parcel using a given class loader. 61 * Reads the state of the superclass. 62 * 63 * @param source parcel to read from 64 * @param loader ClassLoader to use for reading 65 */ AbsSavedState(Parcel source, ClassLoader loader)66 protected AbsSavedState(Parcel source, ClassLoader loader) { 67 Parcelable superState = source.readParcelable(loader); 68 mSuperState = superState != null ? superState : EMPTY_STATE; 69 } 70 getSuperState()71 final public Parcelable getSuperState() { 72 return mSuperState; 73 } 74 describeContents()75 public int describeContents() { 76 return 0; 77 } 78 writeToParcel(Parcel dest, int flags)79 public void writeToParcel(Parcel dest, int flags) { 80 dest.writeParcelable(mSuperState, flags); 81 } 82 83 public static final Parcelable.Creator<AbsSavedState> CREATOR 84 = new Parcelable.ClassLoaderCreator<AbsSavedState>() { 85 86 @Override 87 public AbsSavedState createFromParcel(Parcel in) { 88 return createFromParcel(in, null); 89 } 90 91 @Override 92 public AbsSavedState createFromParcel(Parcel in, ClassLoader loader) { 93 Parcelable superState = in.readParcelable(loader); 94 if (superState != null) { 95 throw new IllegalStateException("superState must be null"); 96 } 97 return EMPTY_STATE; 98 } 99 100 @Override 101 public AbsSavedState[] newArray(int size) { 102 return new AbsSavedState[size]; 103 } 104 }; 105 } 106