Java example source code file (Unsigned.java)

This example Java source code file (Unsigned.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bad, correct, high, low, max_unsigned_int, max_value, runtimeexception, should, string, unexpected

The Unsigned.java Java example source code

/*
 * Copyright (c) 2009, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 4504839 4215269 6322074
 * @summary Basic tests for unsigned operations.
 * @author Joseph D. Darcy
 */
public class Unsigned {
    public static void main(String... args) {
        int errors = 0;

        errors += testRoundtrip();
        errors += testByteToUnsignedInt();
        errors += testShortToUnsignedInt();
        errors += testUnsignedCompare();
        errors += testToUnsignedLong();
        errors += testToStringUnsigned();
        errors += testParseUnsignedInt();
        errors += testDivideAndRemainder();

        if (errors > 0) {
            throw new RuntimeException(errors + " errors found in unsigned operations.");
        }
    }

    private static int testRoundtrip() {
        int errors = 0;

        int[] data = {-1, 0, 1};

        for(int datum : data) {
            if (Integer.parseUnsignedInt(Integer.toBinaryString(datum), 2) != datum) {
                errors++;
                System.err.println("Bad binary roundtrip conversion of " + datum);
            }

            if (Integer.parseUnsignedInt(Integer.toOctalString(datum), 8) != datum) {
                errors++;
                System.err.println("Bad octal roundtrip conversion of " + datum);
            }

            if (Integer.parseUnsignedInt(Integer.toHexString(datum), 16) != datum) {
                errors++;
                System.err.println("Bad hex roundtrip conversion of " + datum);
            }
        }
        return errors;
    }

    private static int testByteToUnsignedInt() {
        int errors = 0;

        for(int i = Byte.MIN_VALUE; i <= Byte.MAX_VALUE; i++) {
            byte datum = (byte) i;
            int ui = Byte.toUnsignedInt(datum);

            if ( (ui & (~0xff)) != 0 ||
                 ((byte)ui != datum )) {
                errors++;
                System.err.printf("Bad conversion of byte %d to unsigned int %d%n",
                                  datum, ui);
            }
        }
        return errors;
    }

    private static int testShortToUnsignedInt() {
        int errors = 0;

        for(int i = Short.MIN_VALUE; i <= Short.MAX_VALUE; i++) {
            short datum = (short) i;
            int ui = Short.toUnsignedInt(datum);

            if ( (ui & (~0xffff)) != 0 ||
                 ((short)ui != datum )) {
                errors++;
                System.err.printf("Bad conversion of short %d to unsigned int %d%n",
                                  datum, ui);
            }
        }
        return errors;
    }

    private static int testUnsignedCompare() {
        int errors = 0;

        int[] data = {
            0,
            1,
            2,
            3,
            0x8000_0000,
            0x8000_0001,
            0x8000_0002,
            0x8000_0003,
            0xFFFF_FFFE,
            0xFFFF_FFFF,
        };

        for(int i : data) {
            for(int j : data) {
                int libraryResult    = Integer.compareUnsigned(i, j);
                int libraryResultRev = Integer.compareUnsigned(j, i);
                int localResult      = compUnsigned(i, j);

                if (i == j) {
                    if (libraryResult != 0) {
                        errors++;
                        System.err.printf("Value 0x%x did not compare as " +
                                          "an unsigned value equal to itself; got %d%n",
                                          i, libraryResult);
                    }
                }

                if (Integer.signum(libraryResult) != Integer.signum(localResult)) {
                    errors++;
                    System.err.printf("Unsigned compare of 0x%x to 0x%x%n:" +
                                      "\texpected sign of %d, got %d%n",
                                      i, j, localResult, libraryResult);
                }

                if (Integer.signum(libraryResult) !=
                    -Integer.signum(libraryResultRev)) {
                    errors++;
                    System.err.printf("signum(compareUnsigned(x, y)) != -signum(compareUnsigned(y,x))" +
                                      " for \t0x%x and 0x%x, computed %d and %d%n",
                                      i, j, libraryResult, libraryResultRev);
                }
            }
        }

        return errors;
    }

    /**
     * Straightforward compare unsigned algorithm.
     */
    private static int compUnsigned(int x, int y) {
        int sign_x = x & Integer.MIN_VALUE;
        int sign_y = y & Integer.MIN_VALUE;

        int mant_x  = x & (~Integer.MIN_VALUE);
        int mant_y  = y & (~Integer.MIN_VALUE);

        if (sign_x == sign_y)
            return Integer.compare(mant_x, mant_y);
        else {
            if (sign_x == 0)
                return -1; // sign x is 0, sign y is 1 => (x < y)
            else
                return 1; //  sign x is 1, sign y is 0 => (x > y)
        }
    }

    private static int testToUnsignedLong() {
        int errors = 0;

        int[] data = {
            0,
            1,
            2,
            3,
            0x1234_5678,
            0x8000_0000,
            0x8000_0001,
            0x8000_0002,
            0x8000_0003,
            0x8765_4321,
            0xFFFF_FFFE,
            0xFFFF_FFFF,
        };

        for(int datum : data) {
            long result = Integer.toUnsignedLong(datum);

            // High-order bits should be zero
            if ((result & 0xffff_ffff_0000_0000L) != 0L) {
                errors++;
                System.err.printf("High bits set converting 0x%x to 0x%x%n",
                                  datum, result);
            }

            // Lower-order bits should be equal to datum.
            int lowOrder = (int)(result & 0x0000_0000_ffff_ffffL);
            if (lowOrder != datum ) {
                errors++;
                System.err.printf("Low bits not preserved converting 0x%x to 0x%x%n",
                                  datum, result);
            }
        }
        return errors;
    }

    private static int testToStringUnsigned() {
        int errors = 0;

        int[] data = {
            0,
            1,
            2,
            3,
            99999,
            100000,
            999999,
            100000,
            999999999,
            1000000000,
            0x1234_5678,
            0x8000_0000,
            0x8000_0001,
            0x8000_0002,
            0x8000_0003,
            0x8765_4321,
            0xFFFF_FFFE,
            0xFFFF_FFFF,
        };

        for(int radix = Character.MIN_RADIX; radix <= Character.MAX_RADIX; radix++) {
            for(int datum : data) {
                String result1 = Integer.toUnsignedString(datum, radix);
                String result2 = Long.toString(Integer.toUnsignedLong(datum), radix);

                if (!result1.equals(result2)) {
                    errors++;
                    System.err.printf("Unexpected string difference converting 0x%x:" +
                                      "\t%s %s%n",
                                      datum, result1, result2);
                }

                if (radix == 10) {
                    String result3 = Integer.toUnsignedString(datum);
                    if (!result2.equals(result3)) {
                        errors++;
                        System.err.printf("Unexpected string difference converting 0x%x:" +
                                          "\t%s %s%n",
                                          datum, result3, result2);
                    }
                }

                int parseResult = Integer.parseUnsignedInt(result1, radix);

                if (parseResult != datum) {
                    errors++;
                        System.err.printf("Bad roundtrip conversion of %d in base %d" +
                                          "\tconverting back ''%s'' resulted in %d%n",
                                          datum, radix, result1,  parseResult);
                }
            }
        }

        return errors;
    }

    private static final long MAX_UNSIGNED_INT = Integer.toUnsignedLong(0xffff_ffff);

    private static int testParseUnsignedInt() {
        int errors = 0;

        // Values include those between signed Integer.MAX_VALUE and
        // unsignted int MAX_VALUE.
        long[] inRange = {
            0L,
            1L,
            10L,
            2147483646L,   // MAX_VALUE - 1
            2147483647L,   // MAX_VALUE
            2147483648L,   // MAX_VALUE + 1

            MAX_UNSIGNED_INT - 1L,
            MAX_UNSIGNED_INT,
        };

        for(long value : inRange) {
            for(int radix = Character.MIN_RADIX; radix <= Character.MAX_RADIX; radix++) {
                String longString = Long.toString(value, radix);
                int intResult = Integer.parseUnsignedInt(longString, radix);

                if (Integer.toUnsignedLong(intResult) != value) {
                    errors++;
                    System.err.printf("Bad roundtrip conversion of %d in base %d" +
                                      "\tconverting back ''%s'' resulted in %d%n",
                                      value, radix, longString,  intResult);
                }
            }
        }

        String[] outOfRange = {
            null,
            "",
            "-1",
            Long.toString(MAX_UNSIGNED_INT + 1L),
            Long.toString(Long.MAX_VALUE)
        };

        for(String s : outOfRange) {
            try {
                int result = Integer.parseUnsignedInt(s);
                errors++; // Should not reach here
                System.err.printf("Unexpected got %d from an unsigned conversion of %s",
                                  result, s);
            } catch(NumberFormatException nfe) {
                ; // Correct result
            }
        }

        return errors;
    }

    private static int testDivideAndRemainder() {
        int errors = 0;

        long[] inRange = {
            0L,
            1L,
            2L,
            2147483646L,   // MAX_VALUE - 1
            2147483647L,   // MAX_VALUE
            2147483648L,   // MAX_VALUE + 1

            MAX_UNSIGNED_INT - 1L,
            MAX_UNSIGNED_INT,
        };

        for(long dividend : inRange) {
            for(long divisor : inRange) {
                int quotient;
                long longQuotient;

                int remainder;
                long longRemainder;

                if (divisor == 0) {
                    try {
                        quotient = Integer.divideUnsigned((int) dividend, (int) divisor);
                        errors++;
                    } catch(ArithmeticException ea) {
                        ; // Expected
                    }

                    try {
                        remainder = Integer.remainderUnsigned((int) dividend, (int) divisor);
                        errors++;
                    } catch(ArithmeticException ea) {
                        ; // Expected
                    }
                } else {
                    quotient = Integer.divideUnsigned((int) dividend, (int) divisor);
                    longQuotient = dividend / divisor;

                    if (quotient != (int)longQuotient) {
                        errors++;
                        System.err.printf("Unexpected unsigned divide result %s on %s/%s%n",
                                          Integer.toUnsignedString(quotient),
                                          Integer.toUnsignedString((int) dividend),
                                          Integer.toUnsignedString((int) divisor));
                    }

                    remainder = Integer.remainderUnsigned((int) dividend, (int) divisor);
                    longRemainder = dividend % divisor;

                    if (remainder != (int)longRemainder) {
                        errors++;
                        System.err.printf("Unexpected unsigned remainder result %s on %s%%%s%n",
                                          Integer.toUnsignedString(remainder),
                                          Integer.toUnsignedString((int) dividend),
                                          Integer.toUnsignedString((int) divisor));
                    }
                }
            }
        }

        return errors;
    }
}