Class FileDrop


  • public class FileDrop
    extends Object
    This class makes it easy to drag and drop files from the operating system to a Java program. Any java.awt.Component can be dropped onto, but only javax.swing.JComponents will indicate the drop event with a changed border.

    To use this class, construct a new FileDrop by passing it the target component and a Listener to receive notification when file(s) have been dropped. Here is an example:

          JPanel myPanel = new JPanel();
          new FileDrop( myPanel, new FileDrop.Listener()
          {   public void filesDropped( java.io.File[] files )
              {   
                  // handle file drop
                  ...
              }   // end filesDropped
          }); // end FileDrop.Listener
     

    You can specify the border that will appear when files are being dragged by calling the constructor with a javax.swing.border.Border. Only JComponents will show any indication with a border.

    You can turn on some debugging features by passing a PrintStream object (such as System.out) into the full constructor. A null value will result in no extra debugging information being output.

    I'm releasing this code into the Public Domain. Enjoy.

    Original author: Robert Harder, rharder@usa.net

    Version:
    1.0
    Author:
    Robert Harder, rharder@usa.net
    • Constructor Detail

      • FileDrop

        public FileDrop​(Component c,
                        FileDrop.Listener listener)
        Constructs a FileDrop with a default light-blue border and, if c is a Container, recursively sets all elements contained within as drop targets, though only the top level container will change borders.
        Parameters:
        c - Component on which files will be dropped.
        listener - Listens for filesDropped.
        Since:
        1.0
      • FileDrop

        public FileDrop​(Component c,
                        boolean recursive,
                        FileDrop.Listener listener)
        Constructor with a default border and the option to recursively set drop targets. If your component is a java.awt.Container, then each of its children components will also listen for drops, though only the parent will change borders.
        Parameters:
        c - Component on which files will be dropped.
        recursive - Recursively set children as drop targets.
        listener - Listens for filesDropped.
        Since:
        1.0
      • FileDrop

        public FileDrop​(PrintStream out,
                        Component c,
                        FileDrop.Listener listener)
        Constructor with a default border and debugging optionally turned on. With Debugging turned on, more status messages will be displayed to out. A common way to use this constructor is with System.out or System.err. A null value for the parameter out will result in no debugging output.
        Parameters:
        out - PrintStream to record debugging info or null for no debugging.
        c - Component on which files will be dropped.
        listener - Listens for filesDropped.
        Since:
        1.0
      • FileDrop

        public FileDrop​(PrintStream out,
                        Component c,
                        boolean recursive,
                        FileDrop.Listener listener)
        Constructor with a default border, debugging optionally turned on and the option to recursively set drop targets. If your component is a java.awt.Container, then each of its children components will also listen for drops, though only the parent will change borders. With Debugging turned on, more status messages will be displayed to out. A common way to use this constructor is with System.out or System.err. A null value for the parameter out will result in no debugging output.
        Parameters:
        out - PrintStream to record debugging info or null for no debugging.
        c - Component on which files will be dropped.
        recursive - Recursively set children as drop targets.
        listener - Listens for filesDropped.
        Since:
        1.0
      • FileDrop

        public FileDrop​(Component c,
                        Border dragBorder,
                        FileDrop.Listener listener)
        Constructor with a specified border
        Parameters:
        c - Component on which files will be dropped.
        dragBorder - Border to use on JComponent when dragging occurs.
        listener - Listens for filesDropped.
        Since:
        1.0
      • FileDrop

        public FileDrop​(Component c,
                        Border dragBorder,
                        boolean recursive,
                        FileDrop.Listener listener)
        Constructor with a specified border and the option to recursively set drop targets. If your component is a java.awt.Container, then each of its children components will also listen for drops, though only the parent will change borders.
        Parameters:
        c - Component on which files will be dropped.
        dragBorder - Border to use on JComponent when dragging occurs.
        recursive - Recursively set children as drop targets.
        listener - Listens for filesDropped.
        Since:
        1.0
      • FileDrop

        public FileDrop​(PrintStream out,
                        Component c,
                        Border dragBorder,
                        FileDrop.Listener listener)
        Constructor with a specified border and debugging optionally turned on. With Debugging turned on, more status messages will be displayed to out. A common way to use this constructor is with System.out or System.err. A null value for the parameter out will result in no debugging output.
        Parameters:
        out - PrintStream to record debugging info or null for no debugging.
        c - Component on which files will be dropped.
        dragBorder - Border to use on JComponent when dragging occurs.
        listener - Listens for filesDropped.
        Since:
        1.0
      • FileDrop

        public FileDrop​(PrintStream out,
                        Component c,
                        Border dragBorder,
                        boolean recursive,
                        FileDrop.Listener listener)
        Full constructor with a specified border and debugging optionally turned on. With Debugging turned on, more status messages will be displayed to out. A common way to use this constructor is with System.out or System.err. A null value for the parameter out will result in no debugging output.
        Parameters:
        out - PrintStream to record debugging info or null for no debugging.
        c - Component on which files will be dropped.
        dragBorder - Border to use on JComponent when dragging occurs.
        recursive - Recursively set children as drop targets.
        listener - Listens for filesDropped.
        Since:
        1.0
    • Method Detail

      • remove

        public static boolean remove​(Component c)
        Removes the drag-and-drop hooks from the component and optionally from the all children. You should call this if you add and remove components after you've set up the drag-and-drop. This will recursively unregister all components contained within c if c is a Container.
        Parameters:
        c - The component to unregister as a drop target
        Since:
        1.0
      • remove

        public static boolean remove​(PrintStream out,
                                     Component c,
                                     boolean recursive)
        Removes the drag-and-drop hooks from the component and optionally from the all children. You should call this if you add and remove components after you've set up the drag-and-drop.
        Parameters:
        out - Optional PrintStream for logging drag and drop messages
        c - The component to unregister
        recursive - Recursively unregister components within a container
        Since:
        1.0
      • main

        public static void main​(String[] args)
        Runs a sample program that shows dropped files