Java file object size returning 0

Question

System.out.print("1");
System.out.println(ts.getComponent());
System.out.println(ts.getTransferable().getTransferData(DataFlavor.javaFileListFlavor));
String dir = ts.getTransferable().getTransferData(DataFlavor.javaFileListFlavor).toString();

File file = new File(dir);
System.out.println(file.getName());
System.out.println(file.getPath());
System.out.println(file.getTotalSpace());

long num = file.length();
System.out.println(num);

Output

1javax.swing.JTable[,0,0,556x64,alignmentX=0.0,alignmentY=0.0,border=javax.swing.plaf.synth.SynthBorder@1baabbd6,flags=251658568,maximumSize=,minimumSize=,preferredSize=,autoCreateColumnsFromModel=true,autoResizeMode=AUTO_RESIZE_SUBSEQUENT_COLUMNS,cellSelectionEnabled=false,editingColumn=-1,editingRow=-1,gridColor=javax.swing.plaf.ColorUIResource[r=35,g=35,b=36],preferredViewportSize=java.awt.Dimension[width=450,height=400],rowHeight=16,rowMargin=0,rowSelectionAllowed=true,selectionBackground=DerivedColor(color=57,105,138 parent=nimbusSelectionBackground offsets=0.0,0.0,0.0,0 pColor=57,105,138,selectionForeground=DerivedColor(color=255,255,255 parent=nimbusLightBackground offsets=0.0,0.0,0.0,0 pColor=255,255,255,showHorizontalLines=false,showVerticalLines=false]
[C:\Users\Ye\Desktop\Spotify.lnk]
Spotify.lnk]
[C:\Users\Ye\Desktop\Spotify.lnk]
0

I dont get how file size is 0 despite testing it with few files

Have you tried checking different file types? i.e., not Windows shortcuts. — Matt Clark
– Matt Clark, Commented Nov 24, 2018 at 4:52

Naman · Accepted Answer · 2018-11-24 05:40:51Z

3

Chances are that you're either checking the length of a directory OR that the specified File doesn't exist.

From the documentation of the File.length, it returns:

The length, in bytes, of the file denoted by this abstract pathname, or 0L if the file does not exist. Some operating systems may return 0L for pathnames denoting system-dependent entities such as devices or pipes.

answered Nov 24, 2018 at 5:40

Naman

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Comments

Pranjal · Accepted Answer · 2018-11-24 08:20:03Z

2

The problem seems to be with the path String you are providing to the File constructor. The value [C:\Users\Ye\Desktop\Spotify.lnk] is not a valid pathname for the File constructor for the file your are trying to access. This is visible in your print statement's output for file.getName() which is Spotify.lnk] and not Spotify.lnk. The file object you are trying to get the size of is a new file with the name Spotify.lnk**]** that has the size 0.
I don't know whether you have any other way to get the file name other than getTransferData(DataFlavor.javaFileListFlavor).toString() but you can try to sanitise the file name using the following code :

    String dirTemp = ts.getTransferable().getTransferData(DataFlavor.javaFileListFlavor).toString();
    dir = dirTemp.substring(1, dirTemp.length() - 1);
    // Then create the file using this dir String.
    File file = new File(dir);

This would work for the current output of getTransferData()#toString() that you are getting, but might not work if, say, someone changes the toString() implementation.

Edit :

As correctly pointed by @MichaelA.Schaffrath, the object returned by ts.getTransferable().getTransferData(DataFlavor.javaFileListFlavor) is actually a List<File>. So, there isn't even a need to construct a new File object again. Just cast the returned value as a List and use the first value for the File object.

edited Nov 24, 2018 at 8:20

answered Nov 24, 2018 at 5:45

Pranjal

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2 Comments

Michael A. Schaffrath Over a year ago

No need for string parsing. He is using DataFlavor.javaFileListFlavor, which means getTransferData will return a java.util.List. He just needs to cast his result from getTransferData to List and get the first element.

Pranjal Over a year ago

@MichaelA.Schaffrath , Thanks I wasn't aware of that... Will update my answer with the same.

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