How to parse this string in Java?

If you want to split the String at the / character, the String.split method will work:

For example:

String s = "prefix/dir1/dir2/dir3/dir4";
String[] tokens = s.split("/");

for (String t : tokens)
  System.out.println(t);

Output

prefix
dir1
dir2
dir3
dir4

Edit

Case with a / in the prefix, and we know what the prefix is:

String s = "slash/prefix/dir1/dir2/dir3/dir4";

String prefix = "slash/prefix/";
String noPrefixStr = s.substring(s.indexOf(prefix) + prefix.length());

String[] tokens = noPrefixStr.split("/");

for (String t : tokens)
  System.out.println(t);

The substring without the prefix "slash/prefix/" is made by the substring method. That String is then run through split.

Output:

dir1
dir2
dir3
dir4

Edit again

If this String is actually dealing with file paths, using the File class is probably more preferable than using string manipulations. Classes like File which already take into account all the intricacies of dealing with file paths is going to be more robust.

...
String str = "bla!/bla/bla/"

String parts[] = str.split("/");

//To get fist "bla!"
String dir1 = parts[0];

In this case, why not use new File("prefix/dir1/dir2/dir3/dir4") and go from there?