Examples of java.util.Comparator

java.util.Comparator
A comparison function, which imposes a total ordering on some collection of objects. Comparators can be passed to a sort method (such as {@link Collections#sort(List,Comparator) Collections.sort} or {@link Arrays#sort(Object[],Comparator) Arrays.sort}) to allow precise control over the sort order. Comparators can also be used to control the order of certain data structures (such as {@link SortedSet sorted sets} or {@link SortedMap sorted maps}), or to provide an ordering for collections of objects that don't have a {@link Comparable natural ordering}.
The ordering imposed by a comparator c on a set of elements S is said to be consistent with equals if and only if c.compare(e1, e2)==0 has the same boolean value as e1.equals(e2) for every e1 and e2 in S.
Caution should be exercised when using a comparator capable of imposing an ordering inconsistent with equals to order a sorted set (or sorted map). Suppose a sorted set (or sorted map) with an explicit comparator c is used with elements (or keys) drawn from a set S. If the ordering imposed by c on S is inconsistent with equals, the sorted set (or sorted map) will behave "strangely." In particular the sorted set (or sorted map) will violate the general contract for set (or map), which is defined in terms of equals.
For example, suppose one adds two elements {@code a} and {@code b} such that{@code (a.equals(b) && c.compare(a, b) != 0)}to an empty {@code TreeSet} with comparator {@code c}. The second {@code add} operation will returntrue (and the size of the tree set will increase) because {@code a} and{@code b} are not equivalent from the tree set's perspective, even thoughthis is contrary to the specification of the {@link Set#add Set.add} method.
Note: It is generally a good idea for comparators to also implement java.io.Serializable, as they may be used as ordering methods in serializable data structures (like {@link TreeSet}, {@link TreeMap}). In order for the data structure to serialize successfully, the comparator (if provided) must implement Serializable.
For the mathematically inclined, the relation that defines the imposed ordering that a given comparator c imposes on a given set of objects S is:
```
 {(x, y) such that c.compare(x, y) <= 0}. 
```
The quotient for this total order is:
```
 {(x, y) such that c.compare(x, y) == 0}. 
```
It follows immediately from the contract for compare that the quotient is an equivalence relation on S, and that the imposed ordering is a total order on S. When we say that the ordering imposed by c on S is consistent with equals, we mean that the quotient for the ordering is the equivalence relation defined by the objects' {@link Object#equals(Object) equals(Object)} method(s):
```
{(x, y) such that x.equals(y)}. 
```
This interface is a member of the Java Collections Framework. @param < T> the type of objects that may be compared by this comparator @author Josh Bloch @author Neal Gafter @version 1.26, 04/21/06 @see Comparable @see java.io.Serializable @since 1.2

    List sortedControls = new ArrayList(controls.length);
    for(int i = 0 ; i < controls.length ; i++) {
      sortedControls.add(controls[i]);
    }
    
    Collections.sort(sortedControls,new Comparator() {
      public int compare(Object o1, Object o2) {
        Control c1 = (Control) o1;
        Control c2 = (Control) o2;
        Object layoutData1 = c1.getLayoutData();
        Object layoutData2 = c2.getLayoutData();

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    ArrayList list = null;
    synchronized (this.blasterInstanceMap) {
      list = new ArrayList(this.blasterInstanceMap.values());
    }
    
    Collections.sort(list, new Comparator(){
      public int compare( Object a, Object b )
            {
        BlasterInstance one = (BlasterInstance)a;
        BlasterInstance two = (BlasterInstance)b;
        if (creationTimestamp)

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      if (sort_thread.isAlive()) return ;
    sort_thread = new JMThread(new JMRunnable() {
      public void JMRun() {
        last_sort_column = columnID;
        last_sort_dir = sortOrder;
        Collections.sort(line_list, new Comparator() {
            public int compare(Object arg0, Object arg1) {
              BufferedTableRow row1 = (BufferedTableRow)arg0;
              BufferedTableRow row2 = (BufferedTableRow)arg1;
                
              T object1 = (T) row1.getData(SWTConstants.ROW_OBJECT_KEY);

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      client.setIdentifier(UIConstants.UPLOAD_PEER_LIST_SOFTWARE_COLUMN_ID);
      client.setModelIndex(UploadPeersModel.CLIENT);
      client.setVisible(_pref.isColumnVisible(UIConstants.UPLOAD_PEER_LIST_SOFTWARE_COLUMN_ID));
      client.setHeaderValue("Client");
      client.setCellRenderer(new ClientTableCellRenderer());
      client.setComparator(new Comparator() {
      public int compare(Object o1, Object o2) {
        String client1 = PeerInfoFormatter.formatPeerSoftware((Peer)o1);
        String client2 = PeerInfoFormatter.formatPeerSoftware((Peer)o2);
        return Misc.compareAllObjects(client1, client2, "toString", true);
      }
      });
      
      table_columns.add(client);
      
      JMTableColumn status = new JMTableColumn();
      status.setIdentifier(UIConstants.UPLOAD_PEER_LIST_STATUS_COLUMN_ID);
      status.setModelIndex(UploadPeersModel.STATUS);
      status.setVisible(_pref.isColumnVisible(UIConstants.UPLOAD_PEER_LIST_STATUS_COLUMN_ID));
      status.setHeaderValue("Status");
      status.setCellRenderer(new StatusTableCellRenderer());
      status.setComparator(new Comparator() {
      public int compare(Object o1, Object o2) {
        Object[] objects1 = (Object[])o1;
        Object[] objects2 = (Object[])o2;
        UploadSession session1 = (UploadSession)objects1[0];
        Peer peer1 = (Peer)objects1[1];

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    type.setIdentifier(UIConstants.SEARCH_FILE_TYPE_COLUMN_ID);
    type.setModelIndex(SearchResultTableModel.TYPE);
    type.setVisible(_pref.isColumnVisible(UIConstants.SEARCH_FILE_TYPE_COLUMN_ID));
    type.setHeaderValue(_._("mainwindow.searchtab.column.filetype"));
    type.setCellRenderer(new TypeTableCellRenderer());
    type.setComparator(new Comparator() {
      public int compare(Object o1, Object o2) {
        String file_type1 = FileFormatter.formatMimeType(((SearchResultItem)o1).getMimeType());
        String file_type2 = FileFormatter.formatMimeType(((SearchResultItem)o2).getMimeType());
        return Misc.compareAllObjects(file_type1, file_type2, "toString", true);
      }

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    upload_speed.setIdentifier(UIConstants.DOWNLOAD_LIST_UPLOAD_SPEED_COLUMN_ID);
    upload_speed.setModelIndex(DownloadTableModel.UPLOAD_SPEED);
    upload_speed.setVisible(_pref.isColumnVisible(UIConstants.DOWNLOAD_LIST_UPLOAD_SPEED_COLUMN_ID));
    upload_speed.setHeaderValue("Up speed");
    upload_speed.setCellRenderer(new UploadSpeedTableCellRenderer());
    upload_speed.setComparator(new Comparator() {
      public int compare(Object o1, Object o2) {
        Float u_speed1 = null;
        Float u_speed2 = null;
        try {
          DownloadSession d_session1 = (DownloadSession)o1;

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    file_type.setIdentifier(UIConstants.SHARED_LIST_FILE_TYPE_COLUMN_ID);
    file_type.setModelIndex(SharedFilesTableModel.TYPE);
    file_type.setVisible(_pref.isColumnVisible(UIConstants.SHARED_LIST_FILE_TYPE_COLUMN_ID));
    file_type.setHeaderValue("Type");
    file_type.setCellRenderer(new FileTypeTableCellRenderer());
    file_type.setComparator(new Comparator() {
      public int compare(Object o1, Object o2) {
        String file_type1 = FileFormatter.formatMimeType(((SharedFile)o1).getMimeType());
        String file_type2 = FileFormatter.formatMimeType(((SharedFile)o2).getMimeType());
        return Misc.compareAllObjects(file_type1, file_type2, "toString", true);
      }      
    });
    
    table_columns.add(file_type);
    
    JMTableColumn file_hash = new JMTableColumn();
    file_hash.setIdentifier(UIConstants.SHARED_LIST_FILE_ID_COLUMN_ID);
    file_hash.setModelIndex(SharedFilesTableModel.HASH);
    file_hash.setVisible(_pref.isColumnVisible(UIConstants.SHARED_LIST_FILE_ID_COLUMN_ID));
    file_hash.setHeaderValue("Hash");
    file_hash.setCellRenderer(new FileHashTableCellRenderer());
    file_hash.setComparator(new GeneralComparator("getFileHash"));
    
    table_columns.add(file_hash);
    
    JMTableColumn completed = new JMTableColumn();
    completed.setIdentifier(UIConstants.SHARED_LIST_COMPLETED_COLUMN_ID);
    completed.setModelIndex(SharedFilesTableModel.COMPLETED);
    completed.setVisible(_pref.isColumnVisible(UIConstants.SHARED_LIST_COMPLETED_COLUMN_ID));
    completed.setHeaderValue("Completed");
    completed.setCellRenderer(new CompletedTableCellRenderer());
    completed.setComparator(new GeneralComparator("getPercentCompleted"));
    completed.setComparator(new Comparator() {
      public int compare(Object o1, Object o2) {
        double completed1 = 100;
        double completed2 = 100;
        SharedFile shared_file1 = (SharedFile)o1;
        SharedFile shared_file2 = (SharedFile)o2;

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  private BucketDefinition createServiceBucket(JRCrosstabGroup group, byte evaluation) throws JRException
  {
    JRCrosstabBucket bucket = group.getBucket();


    Comparator comparator = null;
    JRExpression comparatorExpression = bucket.getComparatorExpression();
    if (comparatorExpression != null)
    {
      comparator = (Comparator) evaluateExpression(comparatorExpression, evaluation);
    }

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   private List sortDelegatesOnServerID(Collection delegates)
   {
      List localDels = new ArrayList(delegates);


      Collections.sort(localDels,
         new Comparator()
         {
            public int compare(Object obj1, Object obj2)
            {
               ClientConnectionFactoryDelegate del1 = (ClientConnectionFactoryDelegate)obj1;
               ClientConnectionFactoryDelegate del2 = (ClientConnectionFactoryDelegate)obj2;

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      List entries = new ArrayList(deliveries.entrySet());
      
      //Sort them in reverse delivery id order
      Collections.sort(entries,
                       new Comparator()
                       {
                           public int compare(Object obj1, Object obj2)
                           {
                              Map.Entry entry1 = (Map.Entry)obj1;
                              Map.Entry entry2 = (Map.Entry)obj2;

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