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      1 /*
      2  * Copyright (C) 2015 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 com.android.messaging.datamodel.binding;
     18 
     19 /**
     20  * Base class for data objects that will be bound to a piece of the UI
     21  */
     22 public abstract class BindableData {
     23     /**
     24      * Called by Binding during unbind to allow data to proactively unregister callbacks
     25      * Data instance should release all listeners that may call back to the host UI
     26      */
     27     protected abstract void unregisterListeners();
     28 
     29     /**
     30      * Key used to identify the piece of UI that the data is currently bound to
     31      */
     32     private String mBindingId;
     33 
     34     /**
     35      * Bind this data to the ui host - checks data is currently unbound
     36      */
     37     public void bind(final String bindingId) {
     38         if (isBound() || bindingId == null) {
     39             throw new IllegalStateException();
     40         }
     41         mBindingId = bindingId;
     42     }
     43 
     44     /**
     45      * Unbind this data from the ui host - checks that the data is currently bound to specified id
     46      */
     47     public void unbind(final String bindingId) {
     48         if (!isBound(bindingId)) {
     49             throw new IllegalStateException();
     50         }
     51         unregisterListeners();
     52         mBindingId = null;
     53     }
     54 
     55     /**
     56      * Check to see if the data is bound to anything
     57      *
     58      * TODO: This should be package private because it's supposed to only be used by Binding,
     59      * however, several classes call this directly.  We want the classes to track what they are
     60      * bound to.
     61      */
     62     protected boolean isBound() {
     63         return (mBindingId != null);
     64     }
     65 
     66     /**
     67      * Check to see if data is still bound with specified bindingId before calling over to ui
     68      */
     69     public boolean isBound(final String bindingId) {
     70         return (bindingId.equals(mBindingId));
     71     }
     72 }
     73