diff options
Diffstat (limited to 'libjava/classpath/java/lang/Integer.java')
| -rw-r--r-- | libjava/classpath/java/lang/Integer.java | 126 |
1 files changed, 102 insertions, 24 deletions
diff --git a/libjava/classpath/java/lang/Integer.java b/libjava/classpath/java/lang/Integer.java index cbf5274f0fc..e5ca4b3428e 100644 --- a/libjava/classpath/java/lang/Integer.java +++ b/libjava/classpath/java/lang/Integer.java @@ -52,6 +52,7 @@ package java.lang; * @author Eric Blake (ebb9@email.byu.edu) * @author Tom Tromey (tromey@redhat.com) * @author Andrew John Hughes (gnu_andrew@member.fsf.org) + * @author Ian Rogers * @since 1.0 * @status updated to 1.5 */ @@ -92,7 +93,12 @@ public final class Integer extends Number implements Comparable<Integer> // these constants control how much we actually cache. private static final int MIN_CACHE = -128; private static final int MAX_CACHE = 127; - private static Integer[] intCache = new Integer[MAX_CACHE - MIN_CACHE + 1]; + private static final Integer[] intCache = new Integer[MAX_CACHE - MIN_CACHE + 1]; + static + { + for (int i=MIN_CACHE; i <= MAX_CACHE; i++) + intCache[i - MIN_CACHE] = new Integer(i); + } /** * The immutable value of this Integer. @@ -126,6 +132,45 @@ public final class Integer extends Number implements Comparable<Integer> } /** + * Return the size of a string large enough to hold the given number + * + * @param num the number we want the string length for (must be positive) + * @param radix the radix (base) that will be used for the string + * @return a size sufficient for a string of num + */ + private static int stringSize(int num, int radix) { + int exp; + if (radix < 4) + { + exp = 1; + } + else if (radix < 8) + { + exp = 2; + } + else if (radix < 16) + { + exp = 3; + } + else if (radix < 32) + { + exp = 4; + } + else + { + exp = 5; + } + int size=0; + do + { + num >>>= exp; + size++; + } + while(num != 0); + return size; + } + + /** * Converts the <code>int</code> to a <code>String</code> using * the specified radix (base). If the radix exceeds * <code>Character.MIN_RADIX</code> or <code>Character.MAX_RADIX</code>, 10 @@ -142,22 +187,40 @@ public final class Integer extends Number implements Comparable<Integer> if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX) radix = 10; - // For negative numbers, print out the absolute value w/ a leading '-'. - // Use an array large enough for a binary number. - char[] buffer = new char[33]; - int i = 33; - boolean isNeg = false; - if (num < 0) + // Is the value negative? + boolean isNeg = num < 0; + + // Is the string a single character? + if (!isNeg && num < radix) + return new String(digits, num, 1, true); + + // Compute string size and allocate buffer + // account for a leading '-' if the value is negative + int size; + int i; + char[] buffer; + if (isNeg) { - isNeg = true; num = -num; // When the value is MIN_VALUE, it overflows when made positive if (num < 0) { + i = size = stringSize(MAX_VALUE, radix) + 2; + buffer = new char[size]; buffer[--i] = digits[(int) (-(num + radix) % radix)]; num = -(num / radix); } + else + { + i = size = stringSize(num, radix) + 1; + buffer = new char[size]; + } + } + else + { + i = size = stringSize(num, radix); + buffer = new char[size]; } do @@ -171,7 +234,7 @@ public final class Integer extends Number implements Comparable<Integer> buffer[--i] = '-'; // Package constructor avoids an array copy. - return new String(buffer, i, 33 - i, true); + return new String(buffer, i, size - i, true); } /** @@ -275,7 +338,7 @@ public final class Integer extends Number implements Comparable<Integer> */ public static Integer valueOf(String s, int radix) { - return new Integer(parseInt(s, radix, false)); + return valueOf(parseInt(s, radix, false)); } /** @@ -291,7 +354,7 @@ public final class Integer extends Number implements Comparable<Integer> */ public static Integer valueOf(String s) { - return new Integer(parseInt(s, 10, false)); + return valueOf(parseInt(s, 10, false)); } /** @@ -306,12 +369,8 @@ public final class Integer extends Number implements Comparable<Integer> { if (val < MIN_CACHE || val > MAX_CACHE) return new Integer(val); - synchronized (intCache) - { - if (intCache[val - MIN_CACHE] == null) - intCache[val - MIN_CACHE] = new Integer(val); - return intCache[val - MIN_CACHE]; - } + else + return intCache[val - MIN_CACHE]; } /** @@ -440,7 +499,7 @@ public final class Integer extends Number implements Comparable<Integer> public static Integer getInteger(String nm, int val) { Integer result = getInteger(nm, null); - return result == null ? new Integer(val) : result; + return result == null ? valueOf(val) : result; } /** @@ -506,7 +565,7 @@ public final class Integer extends Number implements Comparable<Integer> */ public static Integer decode(String str) { - return new Integer(parseInt(str, 10, true)); + return valueOf(parseInt(str, 10, true)); } /** @@ -628,7 +687,14 @@ public final class Integer extends Number implements Comparable<Integer> */ public static int signum(int x) { - return x < 0 ? -1 : (x > 0 ? 1 : 0); + return (x >> 31) | (-x >>> 31); + + // The LHS propagates the sign bit through every bit in the word; + // if X < 0, every bit is set to 1, else 0. if X > 0, the RHS + // negates x and shifts the resulting 1 in the sign bit to the + // LSB, leaving every other bit 0. + + // Hacker's Delight, Section 2-7 } /** @@ -666,10 +732,22 @@ public final class Integer extends Number implements Comparable<Integer> // Package visible for use by Long. static String toUnsignedString(int num, int exp) { - // Use an array large enough for a binary number. + // Compute string length + int size = 1; + int copy = num >>> exp; + while (copy != 0) + { + size++; + copy >>>= exp; + } + // Quick path for single character strings + if (size == 1) + return new String(digits, num, 1, true); + + // Encode into buffer int mask = (1 << exp) - 1; - char[] buffer = new char[32]; - int i = 32; + char[] buffer = new char[size]; + int i = size; do { buffer[--i] = digits[num & mask]; @@ -678,7 +756,7 @@ public final class Integer extends Number implements Comparable<Integer> while (num != 0); // Package constructor avoids an array copy. - return new String(buffer, i, 32 - i, true); + return new String(buffer, i, size - i, true); } /** |
