Create NumbersCache.java

A cache for strings of integers

Author: charlesbr1

quickfixj-core/src/main/java/quickfix/NumbersCache.java

@@ -0,0 +1,74 @@
+/*******************************************************************************
+ * Copyright (c) quickfixengine.org  All rights reserved.
+ *
+ * This file is part of the QuickFIX FIX Engine
+ *
+ * This file may be distributed under the terms of the quickfixengine.org
+ * license as defined by quickfixengine.org and appearing in the file
+ * LICENSE included in the packaging of this file.
+ *
+ * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING
+ * THE WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE.
+ *
+ * See http://www.quickfixengine.org/LICENSE for licensing information.
+ *
+ * Contact [email protected] if any conditions of this licensing
+ * are not clear to you.
+ ******************************************************************************/
+
+package quickfix;
+
+import java.util.ArrayList;
+
+/**
+ * A cache for commonly used string representing numbers.
+ * Hold values from 0 to 999999 and from 1000 to 200 000 000 by step of 1000
+ */
+public final class NumbersCache {
+
+    private static final int littleNumbersLength = 1000000;
+    private static final int bigNumbersLength = 200000;
+    private static final int bigNumbersOffset = 1000;
+    private static final int bigNumbersMax = bigNumbersLength * bigNumbersOffset;
+
+    public static final ArrayList<String> littleNumbers;
+    public static final ArrayList<String> bigNumbers;
+
+    static {
+        littleNumbers = new ArrayList<String>(littleNumbersLength);
+        bigNumbers = new ArrayList<String>(bigNumbersLength);
+        for (int i = 0; i < littleNumbersLength; i++)
+            littleNumbers.add(Integer.toString(i));
+        for (long i = 0; i < bigNumbersLength;)
+            bigNumbers.add(Long.toString(++i * bigNumbersOffset));
+
+    }
+
+    /**
+     * Get the string representing the given number
+     *
+     * @param i the long to convert
+     * @return the String representing the long
+     */
+    public static String get(long i) {
+        if (i < littleNumbersLength)
+            return littleNumbers.get((int)i);
+        if (i <= bigNumbersMax && i % bigNumbersOffset == 0)
+            return bigNumbers.get((int)(i/bigNumbersOffset)-1);
+        return String.valueOf(i);
+    }
+
+    /**
+     * Get the string representing the given double if it's an integer
+     *
+     * @param d the double to convert
+     * @return the String representing the double or null if the double is not an integer
+     */
+    public static String get(double d) {
+        long l = (long)d;
+        if (d == (double)l)
+            return get(l);
+        return null;
+    }
+}