1 /* 2 * Copyright (C) 2007 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.widget; 18 19 import android.database.DataSetObservable; 20 import android.database.DataSetObserver; 21 import android.view.View; 22 import android.view.ViewGroup; 23 24 /** 25 * Common base class of common implementation for an {@link Adapter} that can be 26 * used in both {@link ListView} (by implementing the specialized 27 * {@link ListAdapter} interface) and {@link Spinner} (by implementing the 28 * specialized {@link SpinnerAdapter} interface). 29 */ 30 public abstract class BaseAdapter implements ListAdapter, SpinnerAdapter { 31 private final DataSetObservable mDataSetObservable = new DataSetObservable(); 32 hasStableIds()33 public boolean hasStableIds() { 34 return false; 35 } 36 registerDataSetObserver(DataSetObserver observer)37 public void registerDataSetObserver(DataSetObserver observer) { 38 mDataSetObservable.registerObserver(observer); 39 } 40 unregisterDataSetObserver(DataSetObserver observer)41 public void unregisterDataSetObserver(DataSetObserver observer) { 42 mDataSetObservable.unregisterObserver(observer); 43 } 44 45 /** 46 * Notifies the attached observers that the underlying data has been changed 47 * and any View reflecting the data set should refresh itself. 48 */ notifyDataSetChanged()49 public void notifyDataSetChanged() { 50 mDataSetObservable.notifyChanged(); 51 } 52 53 /** 54 * Notifies the attached observers that the underlying data is no longer valid 55 * or available. Once invoked this adapter is no longer valid and should 56 * not report further data set changes. 57 */ notifyDataSetInvalidated()58 public void notifyDataSetInvalidated() { 59 mDataSetObservable.notifyInvalidated(); 60 } 61 areAllItemsEnabled()62 public boolean areAllItemsEnabled() { 63 return true; 64 } 65 isEnabled(int position)66 public boolean isEnabled(int position) { 67 return true; 68 } 69 getDropDownView(int position, View convertView, ViewGroup parent)70 public View getDropDownView(int position, View convertView, ViewGroup parent) { 71 return getView(position, convertView, parent); 72 } 73 getItemViewType(int position)74 public int getItemViewType(int position) { 75 return 0; 76 } 77 getViewTypeCount()78 public int getViewTypeCount() { 79 return 1; 80 } 81 isEmpty()82 public boolean isEmpty() { 83 return getCount() == 0; 84 } 85 } 86