Go to examplefilefilter. Java File

To restrict the file type when writing code for the open file dialog box today, the following methods are provided in the JDK help documentation:

Jfilechooser chooser = new jfilechooser ();
// Note: source for examplefilefilter can be found in filechooserdemo,
// Under the demo/jfc directory in the JDK.
Examplefilefilter filter = new examplefilefilter ();
Filter. addextension ("jpg ");
Filter. addextension ("GIF ");
Filter. setdescription ("JPG & GIF images ");
Chooser. setfilefilter (filter );
Int returnval = chooser. showopendialog (parent );
If (returnval = jfilechooser. approve_option ){
System. Out. println ("you chose to open this file:" +
Chooser. getselectedfile (). getname ());
}

The examplefilefilter class is used in the class and inherits the filefilter interface. It is stored in j2sdk1.4.2 _ 16 \ demo \ jfc \ filechooserdemo \ SRC. I use JDK 1.6, but this file is unavailable, after being depressed for a long time, I had to install j1.4 again. Now the problem is solved. I extracted the Code as follows:

Import java. Io. file;
Import java. util. hashtable;
Import java. util. enumeration;
Import javax. Swing .*;
Import javax. Swing. filechooser .*;
Public class examplefilefilter extends filefilter {

Private Static string type_unknown = "type unknown ";
Private Static string hidden_file = "hidden file ";

Private hashtable filters = NULL;
Private string description = NULL;
Private string fulldescription = NULL;
Private Boolean useextensionsindescription = true;
Public examplefilefilter (){
This. Filters = new hashtable ();
}
Public examplefilefilter (string extension ){
This (extension, null );
}

Public examplefilefilter (string extension, string description ){
This ();
If (extension! = NULL) addextension (Extension );
If (description! = NULL) setdescription (description );
}
Public examplefilefilter (string [] filters ){
This (filters, null );
}
Public examplefilefilter (string [] filters, string description ){
This ();
For (INT I = 0; I <filters. length; I ++ ){
// Add filters one by one
Addextension (filters [I]);
}
If (description! = NULL) setdescription (description );
}
Public Boolean accept (file F ){
If (F! = NULL ){
If (F. isdirectory ()){
Return true;
}
String extension = getextension (f );
If (extension! = NULL & filters. Get (getextension (F ))! = NULL ){
Return true;
};
}
Return false;
}
Public String getextension (file F ){
If (F! = NULL ){
String filename = f. getname ();
Int I = filename. lastindexof ('.');
If (I> 0 & I <FILENAME. Length ()-1 ){
Return filename. substring (I + 1). tolowercase ();
};
}
Return NULL;
}
Public void addextension (string extension ){
If (filters = NULL ){
Filters = new hashtable (5 );
}
Filters. Put (extension. tolowercase (), this );
Fulldescription = NULL;
}
Public String getdescription (){
If (fulldescription = NULL ){
If (description = NULL | isextensionlistindescription ()){
Fulldescription = Description = NULL? "(": Description + "(";
// Build the description from the extension list
Enumeration extensions = filters. Keys ();
If (extensions! = NULL ){
Fulldescription + = "." + (string) extensions. nextelement ();
While (extensions. hasmoreelements ()){
Fulldescription + = ",." + (string) extensions. nextelement ();
}
}
Fulldescription + = ")";
} Else {
Fulldescription = description;
}
}
Return fulldescription;
}
Public void setdescription (string description ){
This. Description = description;
Fulldescription = NULL;
}
Public void setextensionlistindescription (Boolean B ){
Useextensionsindescription = B;
Fulldescription = NULL;
}
Public Boolean isextensionlistindescription (){
Return useextensionsindescription;
}
}