List file structure within folder or hard drive

This code example lists the files and folders and also the content in all subfolders.

With recursive calls the file/directory tree can be listed with
a relatively small amount of code.

The purpose of the getTabs method and the variable tabCounter is only to
make the output more viewable with indenting for each level.

import java.io.File;

public class FileStructure {

  int tabCounter = 0;

  public void listFilesAndFolders(String folder) {

    File file = new File(folder);

    if (!file.exists() || !file.isDirectory()) {

      System.out.println("Parameter is not a directory");
      System.exit(1);

    }

    File[] fileArray = file.listFiles();

    for (int i = 0; i < fileArray.length; i++) {

      if (fileArray[i].isDirectory()) {

        System.out.println(getTabs() + "- " + fileArray[i].getName());
        tabCounter++;
        listFilesAndFolders(fileArray[i].getAbsolutePath());

      }
      else {

        System.out.println(getTabs() + fileArray[i].getName());
      }
    }
    tabCounter--;

  }

  private String getTabs() {

    StringBuffer buffer = new StringBuffer();
    for (int i = 0; i < tabCounter; i++)
      buffer.append("\t");

    return buffer.toString();
  }

  public static void main(String[] args) {

    FileStructure fileStructure = new FileStructure();
    fileStructure.listFilesAndFolders("C:\\temp");
  }
}

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