Updated AndroidX

app/src/main/java/androidx/room/StringUtil.java

@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package androidx.room.util;
+
+import android.util.Log;
+
+import androidx.annotation.Nullable;
+import androidx.annotation.RestrictTo;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.StringTokenizer;
+
+/**
+ * @hide
+ *
+ * String utilities for Room
+ */
+@RestrictTo(RestrictTo.Scope.LIBRARY_GROUP_PREFIX)
+public class StringUtil {
+
+    @SuppressWarnings("unused")
+    public static final String[] EMPTY_STRING_ARRAY = new String[0];
+    /**
+     * Returns a new StringBuilder to be used while producing SQL queries.
+     *
+     * @return A new or recycled StringBuilder
+     */
+    public static StringBuilder newStringBuilder() {
+        // TODO pool:
+        return new StringBuilder();
+    }
+
+    /**
+     * Adds bind variable placeholders (?) to the given string. Each placeholder is separated
+     * by a comma.
+     *
+     * @param builder The StringBuilder for the query
+     * @param count Number of placeholders
+     */
+    public static void appendPlaceholders(StringBuilder builder, int count) {
+        for (int i = 0; i < count; i++) {
+            builder.append("?");
+            if (i < count - 1) {
+                builder.append(",");
+            }
+        }
+    }
+    /**
+     * Splits a comma separated list of integers to integer list.
+     * <p>
+     * If an input is malformed, it is omitted from the result.
+     *
+     * @param input Comma separated list of integers.
+     * @return A List containing the integers or null if the input is null.
+     */
+    @Nullable
+    public static List<Integer> splitToIntList(@Nullable String input) {
+        if (input == null) {
+            return null;
+        }
+        List<Integer> result = new ArrayList<>();
+        StringTokenizer tokenizer = new StringTokenizer(input, ",");
+        while (tokenizer.hasMoreElements()) {
+            final String item = tokenizer.nextToken();
+            try {
+                result.add(Integer.parseInt(item));
+            } catch (NumberFormatException ex) {
+                Log.e("ROOM", "Malformed integer list", ex);
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Joins the given list of integers into a comma separated list.
+     *
+     * @param input The list of integers.
+     * @return Comma separated string composed of integers in the list. If the list is null, return
+     * value is null.
+     */
+    @Nullable
+    public static String joinIntoString(@Nullable List<Integer> input) {
+        if (input == null) {
+            return null;
+        }
+
+        final int size = input.size();
+        if (size == 0) {
+            return "";
+        }
+        StringBuilder sb = new StringBuilder();
+        for (int i = 0; i < size; i++) {
+            sb.append(Integer.toString(input.get(i)));
+            if (i < size - 1) {
+                sb.append(",");
+            }
+        }
+        return sb.toString();
+    }
+
+    private StringUtil() {
+    }
+}