HADOOP-12209 Comparable type should be in FileStatus. (Yong Zhang via stevel)

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -972,6 +972,9 @@ Release 2.8.0 - UNRELEASED
     HADOOP-12235 hadoop-openstack junit & mockito dependencies should be
     "provided". (Ted Yu via stevel)
 
+    HADOOP-12209 Comparable type should be in FileStatus.
+    (Yong Zhang via stevel)
+
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileStatus.java

@@ -31,7 +31,7 @@ import org.apache.hadoop.io.Writable;
  */
 @InterfaceAudience.Public
 @InterfaceStability.Stable
-public class FileStatus implements Writable, Comparable {
+public class FileStatus implements Writable, Comparable<FileStatus> {
 
   private Path path;
   private long length;
@@ -323,19 +323,14 @@ public class FileStatus implements Writable, Comparable {
   }
 
   /**
-   * Compare this object to another object
+   * Compare this FileStatus to another FileStatus
-   * 
+   * @param   o the FileStatus to be compared.
-   * @param   o the object to be compared.
    * @return  a negative integer, zero, or a positive integer as this object
    *   is less than, equal to, or greater than the specified object.
-   * 
-   * @throws ClassCastException if the specified object's is not of 
-   *         type FileStatus
    */
   @Override
-  public int compareTo(Object o) {
+  public int compareTo(FileStatus o) {
-    FileStatus other = (FileStatus)o;
+    return this.getPath().compareTo(o.getPath());
-    return this.getPath().compareTo(other.getPath());
   }
   
   /** Compare if this object is equal to another object

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/LocatedFileStatus.java

@@ -90,17 +90,13 @@ public class LocatedFileStatus extends FileStatus {
   }
   
   /**
-   * Compare this object to another object
+   * Compare this FileStatus to another FileStatus
-   * 
+   * @param   o the FileStatus to be compared.
-   * @param   o the object to be compared.
    * @return  a negative integer, zero, or a positive integer as this object
    *   is less than, equal to, or greater than the specified object.
-   * 
-   * @throws ClassCastException if the specified object's is not of 
-   *         type FileStatus
    */
   @Override
-  public int compareTo(Object o) {
+  public int compareTo(FileStatus o) {
     return super.compareTo(o);
   }
   

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/ViewFsLocatedFileStatus.java

@@ -18,6 +18,7 @@
 package org.apache.hadoop.fs.viewfs;
 
 import org.apache.hadoop.fs.BlockLocation;
+import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.LocatedFileStatus;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.permission.FsPermission;
@@ -120,7 +121,7 @@ class ViewFsLocatedFileStatus extends LocatedFileStatus {
   }
 
   @Override
-  public int compareTo(Object o) {
+  public int compareTo(FileStatus o) {
     return super.compareTo(o);
   }
 

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestFileStatus.java

@@ -26,6 +26,9 @@ import java.io.DataInputStream;
 import java.io.DataOutput;
 import java.io.DataOutputStream;
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 
 import org.junit.Test;
 import org.apache.commons.logging.Log;
@@ -183,6 +186,25 @@ public class TestFileStatus {
     validateToString(fileStatus);
   }
   
+  @Test
+  public void testCompareTo() throws IOException {
+    Path path1 = new Path("path1");
+    Path path2 = new Path("path2");
+    FileStatus fileStatus1 =
+        new FileStatus(1, true, 1, 1, 1, 1, FsPermission.valueOf("-rw-rw-rw-"),
+            "one", "one", null, path1);
+    FileStatus fileStatus2 =
+        new FileStatus(1, true, 1, 1, 1, 1, FsPermission.valueOf("-rw-rw-rw-"),
+            "one", "one", null, path2);
+    assertTrue(fileStatus1.compareTo(fileStatus2) < 0);
+    assertTrue(fileStatus2.compareTo(fileStatus1) > 0);
+
+    List<FileStatus> statList = new ArrayList<>();
+    statList.add(fileStatus1);
+    statList.add(fileStatus2);
+    assertTrue(Collections.binarySearch(statList, fileStatus1) > -1);
+  }
+
   /**
    * Check that toString produces the expected output for a symlink.
    */