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import java.io.File;

public class Main {
    public static void main(String[] argv) throws Exception {
        System.out.println("Traversing directories");
        File dir = new File("/www/java"); // Directory to be traversed
        visitAllDirsAndFiles(dir);
    }
    public static void visitAllDirsAndFiles(File dir) {
        System.out.println(dir);
        if (dir.isDirectory()) {
            String[] children = dir.list();
            for (int i = 0; i < children.length; i++) {
                visitAllDirsAndFiles(new File(dir, children[i]));
            }
        }
    }
}

Traversing directories
/www/java
/www/java/Car.class
/www/java/FileUtil.class
/www/java/FileUtil.java
/www/java/HelloWorld.class
/www/java/HelloWorld.java
/www/java/HelloWorldDebug.class
/www/java/HelloWorldDebug.java
/www/java/Main$1.class
/www/java/Main.class
/www/java/Main.java
/www/java/MainClass.class
/www/java/MainClass.java
/www/java/MyClass.class
/www/java/outfilename
/www/java/test.log