像ls这样的java中的格式化输出

Question

I have list of names of files and directories in directory for example:

List<String> list = new ArrayList<Strings>(); /* list of files */

and I need to print it like command ls in linux do that.

a.txt file1.txt       filewithverylongname.txt Folder1
g.txt G_longfile2.txt h.txt                    i.txt

Number of columns depends on number of files and size of columns depends on length of each file or directory name in same column. If I know number of files I would use something in in this link but the number of files or directories could be variable .. How can I do it?

Answer 1

To get number of files in folder

File file = new File("D:\\AnyFolder");
if(file.isDirectory()) {
   File[] listFiles = file.listFiles();
   System.out.println("Total files in folder : " + listFiles.length );
}

Answer 2

I believe this would satisfy your requirement:

import java.io.File;

public class Ls {

    private static final int NUM_COLUMNS = 3;
    private static final int SEPARATING_SPACE_LENGTH = 2;

    public static void main(String[] args) {
        File file = new File("C:/WINDOWS");
        if(file.isDirectory()) {
           File[] listFiles = file.listFiles();
           list(listFiles);
        }
    }

    private static void list(File[] files) {
        int[] maxLength = new int[NUM_COLUMNS];

        for (int i = 0; i < files.length; i++) {
            int fileLength  = files[i].getName().length();
            int columnIndex = i % NUM_COLUMNS; 

            if (maxLength[columnIndex] < fileLength) {
                maxLength[columnIndex] = fileLength;
            }   
        }

        for (int i = 0; i < files.length; i++) {
            String fileName = files[i].getName();
            System.out.print(fileName);
            for (int j = 0; j < maxLength[i % NUM_COLUMNS] - fileName.length() + SEPARATING_SPACE_LENGTH; j++) {
                System.out.print(" ");
            }

            if ((i + 1) % NUM_COLUMNS == 0) {
                System.out.print("\n");
            }
        }
    }

}

Let me know if it's not clear.

Thanks,
EG