test/java/util/Collections/ReverseOrder.java

Print this page
rev 6620 : 8001667: Comparator combinators and extension methods
Reviewed-by: mduigou, briangoetz
Contributed-by: henry.jen@oracle.com


   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /*
  25  * @test
  26  * @bug 4593209
  27  * @summary Reverse comparator was subtly broken
  28  * @author Josh bloch
  29  */
  30 
  31 import java.util.*;

  32 
  33 public class ReverseOrder {

























  34     public static void main(String[] args) throws Exception {
  35         Foo[] a = { new Foo(2), new Foo(3), new Foo(1) };
  36         List list = Arrays.asList(a);
  37         Collections.sort(list, Collections.reverseOrder());

  38 
  39         Foo[] golden = { new Foo(3), new Foo(2), new Foo(1) };
  40         List goldenList = Arrays.asList(golden);
  41         if (!list.equals(goldenList))






  42             throw new Exception(list.toString());
  43     }
  44 }
  45 
  46 class Foo implements Comparable {
  47     int val;
  48     Foo(int i) { val = i; }
  49 
  50     public int compareTo(Object o) {
  51         Foo f = (Foo)o;
  52         return (val < f.val ? Integer.MIN_VALUE : (val == f.val ? 0 : 1));
  53     }
  54 
  55     public boolean equals(Object o) {
  56         return o instanceof Foo && ((Foo)o).val == val;
  57     }
  58 
  59     public int hashCode()    { return val; }
  60 
  61     public String toString() { return Integer.toString(val); }


   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /*
  25  * @test
  26  * @bug 4593209 8001667
  27  * @summary Reverse comparator was subtly broken
  28  * @author Josh bloch
  29  */
  30 
  31 import java.util.*;
  32 import java.io.*;
  33 
  34 public class ReverseOrder {
  35     static byte[] serialBytes(Object o) {
  36         try {
  37             ByteArrayOutputStream bos = new ByteArrayOutputStream();
  38             ObjectOutputStream oos = new ObjectOutputStream(bos);
  39             oos.writeObject(o);
  40             oos.flush();
  41             oos.close();
  42             return bos.toByteArray();
  43         } catch (Throwable t) {
  44             throw new Error(t);
  45         }
  46     }
  47 
  48     @SuppressWarnings("unchecked")
  49     static <T> T serialClone(T o) {
  50         try {
  51             ObjectInputStream ois = new ObjectInputStream
  52                 (new ByteArrayInputStream(serialBytes(o)));
  53             T clone = (T) ois.readObject();
  54             return clone;
  55         } catch (Throwable t) {
  56             throw new Error(t);
  57         }
  58     }
  59 
  60     public static void main(String[] args) throws Exception {
  61         Foo[] a = { new Foo(2), new Foo(3), new Foo(1) };
  62         List list = Arrays.asList(a);
  63         Comparator cmp = Collections.reverseOrder();
  64         Collections.sort(list, cmp);
  65 
  66         Foo[] golden = { new Foo(3), new Foo(2), new Foo(1) };
  67         List goldenList = Arrays.asList(golden);
  68         if (!list.equals(goldenList))
  69             throw new Exception(list.toString());
  70 
  71         Comparator clone = serialClone(cmp);
  72         List list2 = Arrays.asList(a);
  73         Collections.sort(list2, clone);
  74         if (!list2.equals(goldenList))
  75             throw new Exception(list.toString());
  76     }
  77 }
  78 
  79 class Foo implements Comparable {
  80     int val;
  81     Foo(int i) { val = i; }
  82 
  83     public int compareTo(Object o) {
  84         Foo f = (Foo)o;
  85         return (val < f.val ? Integer.MIN_VALUE : (val == f.val ? 0 : 1));
  86     }
  87 
  88     public boolean equals(Object o) {
  89         return o instanceof Foo && ((Foo)o).val == val;
  90     }
  91 
  92     public int hashCode()    { return val; }
  93 
  94     public String toString() { return Integer.toString(val); }