Thread: List all directories under a given directory

import java.util.HashMap;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
 
//save this code to listreps.java
//compile with >javac -Xlint listreps.java
//example run with >java listreps c:/windows
//the above command will list recursively all directories under the windows directory
//I tested it on my windows directory and it listed more than 30000 sub directories.
 //So please wait that the program finishes.
 
class rept{
private long cnt=0;
private String dirIn="";
private HashMap hm = new HashMap(0,90000);
 
void setDir(String dr){
	dirIn=dr.replace("\\","/");
 
}
 
 
HashMap getReps(){
        long bk=0;
        cnt=0;
        String newline = System.getProperty("line.separator");
 
try{
	FileWriter facd = new FileWriter("c:/outdirs/da/da.txt",true);//path of file where directories that could not be opened are listed
	while(true){ //4
	   	try{
			String listf[] = new File(dirIn).list();
			int nlistf = listf.length;
		     if(nlistf>0){ //3
			       FileWriter filrep = new FileWriter("c:/outdirs/testdirs.txt",true);//path of file where directories are listed
			       int flg=0;
			         for(int i=0;i<nlistf;i++){ //2
				        String pth = dirIn+"/"+listf[i];
			   	       if(new File(pth).isDirectory()){ //1
					         cnt=cnt+1;
				           filrep.write(newline+cnt+","+pth);
 
					         hm.put(cnt,pth);
					         flg=1;
				          }//end 1
 
			         }//end 2
				  filrep.close();
 
		    }//end 3
 
		   }catch(NullPointerException ne){
	        	facd.write(newline+"bk="+bk+" - dirIn="+ dirIn);
		   }catch(IOException ie){
		   }//end catchs(ne,ie)
 
		bk=bk+1;
		if(bk==cnt+1) break;
 
		dirIn=(String) hm.get(bk);		
		}//end 4
 
		facd.close();
 
   }catch(IOException ioe){
	    hm.put(0,"file da not closed!");
   }//end catchs(ioe)
 
return hm;
}//end getReps
 
 
long getCntreps(){
	return cnt;
}//end getCntrep
 
}//end class rept
 
 
public class listreps{
public static void main(String args[]){
	rept rp=new rept();
	rp.setDir(args[0]);
	HashMap ham=rp.getReps();
 
	long cntreps=rp.getCntreps();
 
System.out.println("Total number of directories="+cntreps);
ham.clear();	
}//end main
}//end class listreps

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