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      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 com.android.dx.dex.file;
     18 
     19 /**
     20  * An item in a Dalvik file which is referenced by index.
     21  */
     22 public abstract class IndexedItem extends Item {
     23     /** {@code >= -1;} assigned index of the item, or {@code -1} if not
     24      * yet assigned */
     25     private int index;
     26 
     27     /**
     28      * Constructs an instance. The index is initially unassigned.
     29      */
     30     public IndexedItem() {
     31         index = -1;
     32     }
     33 
     34     /**
     35      * Gets whether or not this instance has been assigned an index.
     36      *
     37      * @return {@code true} iff this instance has been assigned an index
     38      */
     39     public final boolean hasIndex() {
     40         return (index >= 0);
     41     }
     42 
     43     /**
     44      * Gets the item index.
     45      *
     46      * @return {@code >= 0;} the index
     47      * @throws RuntimeException thrown if the item index is not yet assigned
     48      */
     49     public final int getIndex() {
     50         if (index < 0) {
     51             throw new RuntimeException("index not yet set");
     52         }
     53 
     54         return index;
     55     }
     56 
     57     /**
     58      * Sets the item index. This method may only ever be called once
     59      * per instance, and this will throw a {@code RuntimeException} if
     60      * called a second (or subsequent) time.
     61      *
     62      * @param index {@code >= 0;} the item index
     63      */
     64     public final void setIndex(int index) {
     65         if (this.index != -1) {
     66             throw new RuntimeException("index already set");
     67         }
     68 
     69         this.index = index;
     70     }
     71 
     72     /**
     73      * Gets the index of this item as a string, suitable for including in
     74      * annotations.
     75      *
     76      * @return {@code non-null;} the index string
     77      */
     78     public final String indexString() {
     79         return '[' + Integer.toHexString(index) + ']';
     80     }
     81 }
     82