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      1 /*
      2  * Copyright (C) 2010 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.common.content;
     18 
     19 import java.util.Arrays;
     20 import java.util.HashMap;
     21 import java.util.Map;
     22 
     23 /**
     24  * A convenience wrapper for a projection map.  Makes it easier to create and use projection maps.
     25  */
     26 public class ProjectionMap extends HashMap<String, String> {
     27 
     28     public static class Builder {
     29 
     30         private ProjectionMap mMap = new ProjectionMap();
     31 
     32         public Builder add(String column) {
     33             mMap.putColumn(column, column);
     34             return this;
     35         }
     36 
     37         public Builder add(String alias, String expression) {
     38             mMap.putColumn(alias, expression + " AS " + alias);
     39             return this;
     40         }
     41 
     42         public Builder addAll(String[] columns) {
     43             for (String column : columns) {
     44                 add(column);
     45             }
     46             return this;
     47         }
     48 
     49         public Builder addAll(ProjectionMap map) {
     50             for (Map.Entry<String, String> entry : map.entrySet()) {
     51                 mMap.putColumn(entry.getKey(), entry.getValue());
     52             }
     53             return this;
     54         }
     55 
     56         public ProjectionMap build() {
     57             String[] columns = new String[mMap.size()];
     58             mMap.keySet().toArray(columns);
     59             Arrays.sort(columns);
     60             mMap.mColumns = columns;
     61             return mMap;
     62         }
     63 
     64     }
     65 
     66     private String[] mColumns;
     67 
     68     public static Builder builder() {
     69         return new Builder();
     70     }
     71 
     72     /**
     73      * Returns a sorted array of all column names in the projection map.
     74      */
     75     public String[] getColumnNames() {
     76         return mColumns;
     77     }
     78 
     79     private void putColumn(String alias, String column) {
     80         super.put(alias, column);
     81     }
     82 
     83     @Override
     84     public String put(String key, String value) {
     85         throw new UnsupportedOperationException();
     86     }
     87 
     88     @Override
     89     public void putAll(Map<? extends String, ? extends String> map) {
     90         throw new UnsupportedOperationException();
     91     }
     92 }
     93