SelectionBuilder.java revision aafbe295d67686870c64c74a59e589d1dfb506fa 
1/*
2 * Copyright (C) 2011 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
17package com.android.providers.contacts.util;
18
19import android.text.TextUtils;
20
21import java.util.ArrayList;
22import java.util.List;
23
24/**
25 * Builds a selection clause by concatenating several clauses with AND.
26 */
27public class SelectionBuilder {
28    private static final String[] EMPTY_STRING_ARRAY =  new String[0];
29    private final List<String> mWhereClauses;
30
31    /**
32     * @param baseSelection The base selection to start with. This is typically
33     *      the user supplied selection arg. Pass null if no base selection is
34     *      required.
35     */
36    public SelectionBuilder(String baseSelection) {
37        mWhereClauses = new ArrayList<String>();
38        addClause(baseSelection);
39    }
40
41    /**
42     * Adds a new clause to the selection. Nothing is added if the supplied clause
43     * is null or empty.
44     */
45    public SelectionBuilder addClause(String clause) {
46        if (!TextUtils.isEmpty(clause)) {
47            mWhereClauses.add(clause);
48        }
49        return this;
50    }
51
52    /**
53     * Returns a combined selection clause with AND of all clauses added using
54     * {@link #addClause(String)}. Returns null if no clause has been added or
55     * only null/empty clauses have been added till now.
56     */
57    public String build() {
58        if (mWhereClauses.size() == 0) {
59            return null;
60        }
61        return DbQueryUtils.concatenateClauses(mWhereClauses.toArray(EMPTY_STRING_ARRAY));
62    }
63}
64