6879143: java.math.BigInteger misses the xxxValueExact methods

Reviewed-by: alanb

src/share/classes/java/math/BigInteger.java

@@ -2919,6 +2919,7 @@ public class BigInteger extends Number implements Comparable<BigInteger> {
      * result with the opposite sign.
      *
      * @return this BigInteger converted to an {@code int}.
+     * @see #intValueExact()
      */
     public int intValue() {
         int result = 0;
@@ -2939,6 +2940,7 @@ public class BigInteger extends Number implements Comparable<BigInteger> {
      * result with the opposite sign.
      *
      * @return this BigInteger converted to a {@code long}.
+     * @see #longValueExact()
      */
     public long longValue() {
         long result = 0;
@@ -3382,4 +3384,84 @@ public class BigInteger extends Number implements Comparable<BigInteger> {
         }
         return result;
     }
+
+    /**
+     * Converts this {@code BigInteger} to a {@code long}, checking
+     * for lost information.  If the value of this {@code BigInteger}
+     * is out of the range of the {@code long} type, then an
+     * {@code ArithmeticException} is thrown.
+     *
+     * @return this {@code BigInteger} converted to a {@code long}.
+     * @throws ArithmeticException if the value of {@code this} will
+     * not exactly fit in a {@code long}.
+     * @see BigInteger#longValue
+     * @since  1.8
+     */
+    public long longValueExact() {
+        if (mag.length <= 2 && bitLength() <= 63)
+            return longValue();
+        else
+            throw new ArithmeticException("BigInteger out of long range");
+    }
+
+    /**
+     * Converts this {@code BigInteger} to an {@code int}, checking
+     * for lost information.  If the value of this {@code BigInteger}
+     * is out of the range of the {@code int} type, then an
+     * {@code ArithmeticException} is thrown.
+     *
+     * @return this {@code BigInteger} converted to an {@code int}.
+     * @throws ArithmeticException if the value of {@code this} will
+     * not exactly fit in a {@code int}.
+     * @see BigInteger#intValue
+     * @since  1.8
+     */
+    public int intValueExact() {
+        if (mag.length <= 1 && bitLength() <= 31)
+            return intValue();
+        else
+            throw new ArithmeticException("BigInteger out of int range");
+    }
+
+    /**
+     * Converts this {@code BigInteger} to a {@code short}, checking
+     * for lost information.  If the value of this {@code BigInteger}
+     * is out of the range of the {@code short} type, then an
+     * {@code ArithmeticException} is thrown.
+     *
+     * @return this {@code BigInteger} converted to a {@code short}.
+     * @throws ArithmeticException if the value of {@code this} will
+     * not exactly fit in a {@code short}.
+     * @see BigInteger#shortValue
+     * @since  1.8
+     */
+    public short shortValueExact() {
+        if (mag.length <= 1 && bitLength() <= 31) {
+            int value = intValue();
+            if (value >= Short.MIN_VALUE && value <= Short.MAX_VALUE)
+                return shortValue();
+        }
+        throw new ArithmeticException("BigInteger out of short range");
+    }
+
+    /**
+     * Converts this {@code BigInteger} to a {@code byte}, checking
+     * for lost information.  If the value of this {@code BigInteger}
+     * is out of the range of the {@code byte} type, then an
+     * {@code ArithmeticException} is thrown.
+     *
+     * @return this {@code BigInteger} converted to a {@code byte}.
+     * @throws ArithmeticException if the value of {@code this} will
+     * not exactly fit in a {@code byte}.
+     * @see BigInteger#byteValue
+     * @since  1.8
+     */
+    public byte byteValueExact() {
+        if (mag.length <= 1 && bitLength() <= 31) {
+            int value = intValue();
+            if (value >= Byte.MIN_VALUE && value <= Byte.MAX_VALUE)
+                return byteValue();
+        }
+        throw new ArithmeticException("BigInteger out of byte range");
+    }
 }

test/java/math/BigInteger/TestValueExact.java

+/*
+ * Copyright (c) 2011, 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 6371401
+ * @summary Tests of fooValueExact methods
+ * @author Joseph D. Darcy
+ */
+import java.math.BigInteger;
+
+public class TestValueExact {
+    public static void main(String... args) {
+        int errors = 0;
+
+        errors += testLongValueExact();
+        errors += testIntValueExact();
+        errors += testShortValueExact();
+        errors += testByteValueExact();
+
+        if (errors > 0)
+            throw new RuntimeException();
+    }
+
+    private static int testLongValueExact() {
+        int errors = 0;
+        BigInteger[] inRange = {
+            BigInteger.valueOf(Long.MIN_VALUE),
+            BigInteger.ZERO,
+            BigInteger.valueOf(Long.MAX_VALUE)
+        };
+
+        BigInteger[] outOfRange = {
+            BigInteger.valueOf(Long.MIN_VALUE).subtract(BigInteger.ONE),
+            BigInteger.valueOf(Long.MAX_VALUE).add(BigInteger.ONE)
+        };
+
+        for (BigInteger bi : inRange) {
+            if (bi.longValueExact() != bi.longValue()) {
+                System.err.println("Mismatching int conversion for " + bi);
+                errors++;
+            }
+        }
+
+        for (BigInteger bi : outOfRange) {
+            try {
+                long value = bi.longValueExact();
+                System.err.println("Failed to get expected exception on " +
+                                   bi + " got " + value);
+                errors++;
+            } catch(ArithmeticException ae) {
+                ; // Expected
+            }
+        }
+        return errors;
+    }
+
+    private static int testIntValueExact() {
+        int errors = 0;
+        BigInteger[] inRange = {
+            BigInteger.valueOf(Integer.MIN_VALUE),
+            BigInteger.ZERO,
+            BigInteger.ONE,
+            BigInteger.TEN,
+            BigInteger.valueOf(Integer.MAX_VALUE)
+        };
+
+        BigInteger[] outOfRange = {
+            BigInteger.valueOf((long)Integer.MIN_VALUE - 1),
+            BigInteger.valueOf((long)Integer.MAX_VALUE + 1)
+        };
+
+        for (BigInteger bi : inRange) {
+            if (bi.intValueExact() != bi.intValue()) {
+                System.err.println("Mismatching int conversion for " + bi);
+                errors++;
+            }
+        }
+
+        for (BigInteger bi : outOfRange) {
+            try {
+                int value = bi.intValueExact();
+                System.err.println("Failed to get expected exception on " +
+                                   bi + " got " + value);
+                errors++;
+            } catch(ArithmeticException ae) {
+                ; // Expected
+            }
+        }
+        return errors;
+    }
+
+    private static int testShortValueExact() {
+        int errors = 0;
+        BigInteger[] inRange = {
+            BigInteger.valueOf(Short.MIN_VALUE),
+            BigInteger.ZERO,
+            BigInteger.ONE,
+            BigInteger.TEN,
+            BigInteger.valueOf(Short.MAX_VALUE)
+        };
+
+        BigInteger[] outOfRange = {
+            BigInteger.valueOf((long)Integer.MIN_VALUE - 1),
+            BigInteger.valueOf((long)Integer.MIN_VALUE),
+            BigInteger.valueOf(   (int)Short.MIN_VALUE - 1),
+            BigInteger.valueOf(   (int)Short.MAX_VALUE + 1),
+            BigInteger.valueOf((long)Integer.MAX_VALUE),
+            BigInteger.valueOf((long)Integer.MAX_VALUE + 1)
+        };
+
+        for (BigInteger bi : inRange) {
+            if (bi.shortValueExact() != bi.shortValue()) {
+                System.err.println("Mismatching short  conversion for " + bi);
+                errors++;
+            }
+        }
+
+        for (BigInteger bi : outOfRange) {
+            try {
+                int value = bi.shortValueExact();
+                System.err.println("Failed to get expected exception on " +
+                                   bi + " got " + value);
+                errors++;
+            } catch(ArithmeticException ae) {
+                ; // Expected
+            }
+        }
+        return errors;
+    }
+
+    private static int testByteValueExact() {
+        int errors = 0;
+        BigInteger[] inRange = {
+            BigInteger.valueOf(Byte.MIN_VALUE),
+            BigInteger.valueOf(0),
+            BigInteger.ONE,
+            BigInteger.TEN,
+            BigInteger.valueOf(Byte.MAX_VALUE)
+        };
+
+        BigInteger[] outOfRange = {
+            BigInteger.valueOf((long)Integer.MIN_VALUE - 1),
+            BigInteger.valueOf((long)Integer.MIN_VALUE),
+            BigInteger.valueOf(   (int)Short.MIN_VALUE - 1),
+            BigInteger.valueOf(   (int)Short.MIN_VALUE),
+            BigInteger.valueOf(    (int)Byte.MIN_VALUE - 1),
+            BigInteger.valueOf(    (int)Byte.MAX_VALUE + 1),
+            BigInteger.valueOf(   (int)Short.MAX_VALUE + 1),
+            BigInteger.valueOf(   (int)Short.MAX_VALUE),
+            BigInteger.valueOf((long)Integer.MAX_VALUE),
+            BigInteger.valueOf((long)Integer.MAX_VALUE + 1)
+        };
+
+        for (BigInteger bi : inRange) {
+            if (bi.byteValueExact() != bi.byteValue()) {
+                System.err.println("Mismatching byte conversion for " + bi);
+                errors++;
+            }
+        }
+
+        for (BigInteger bi : outOfRange) {
+            try {
+                int value = bi.byteValueExact();
+                System.err.println("Failed to get expected exception on " +
+                                   bi + " got " + value);
+                errors++;
+            } catch(ArithmeticException ae) {
+                ; // Expected
+            }
+        }
+        return errors;
+    }
+}