Shorthand to create a path in Java?

Question

I have a code example which creates paths like this :

    String path = System.getProperty("user.dir") + File.separator + "games" + File.separator + "game.exe";

It is irritating and difficult to type File.separator repeatedly. Is there a shorter way to create the path ? I created a custom function to do that, but I am not sure if it is the right way. Please advise.

//Ex. getPath("downloads", "games", "racing.exe") ---> \downloads\games\racing.exe
public static String getPath(String...pathFragments){
    StringBuilder sb = new StringBuilder(File.separator);

    for(int i = 0; i < pathFragments.length-1; i++){
        sb.append(pathFragments[i] + File.separator);
    }

    //Append last pathFragment.
    sb.append(pathFragments[pathFragments.length-1]);

    return sb.toString();
}

[`Paths.get`](https://docs.oracle.com/javase/7/docs/api/java/nio/file/Paths.html#get(java.lang.String,%20java.lang.String...)) would be easier. — Andy Turner, Aug 24 '20 at 18:30
See interface [`java.nio.file.Path`](https://docs.oracle.com/javase/8/docs/api/java/nio/file/Path.html) There is also a [tutorial](https://docs.oracle.com/javase/tutorial/essential/io/path.html) — Abra, Aug 24 '20 at 18:30
In case of pure String based solution your method can be reduced to `public static String getPath(String... pathFragments){ return String.join(File.separator, pathFragments); }` — Pshemo, Aug 24 '20 at 18:37
BTW in your original method `sb.append(pathFragments[i] + File.separator);` should be `sb.append(pathFragments[i]).append(File.separator);` to avoid `+` representing concatenation as it needs to crate yet another StringBuilder which defeats main purpose of `sb`. OR use StringJoiner with delimiter set to `File.separator` and in loop focus only on adding actual data (File.separator will be added automatically) — Pshemo, Aug 24 '20 at 18:38

Joni · Accepted Answer · 2020-08-24T19:24:03.997

4

First thought: Why do you bother with File.separator? Use the cross-platform system-independent file separator character / instead.

String path = System.getProperty("user.dir") + "/games/game.exe";

The only use for File.separator is if you are constructing a file path for a user interface, and want to show the path string to the user, and don't want to confuse Windows users by mixing / and \ in the path.

Second thought: Unless you have a compelling reason to work with Strings, use Paths.get. Compelling reasons include staying backwards compatible with ancient versions of Java or libraries.

// You probably don't need to add System.getProperty("user.dir")
// Relative paths are resolved against current working directory
Path path = Paths.get("games/game.exe");

Third thought: Use String.join instead of StringBuilder.append

public static String getPath(String... pathFragments) {
    return File.separator + String.join(File.separator, pathFragments);
}

edited Aug 24 '20 at 19:24

answered Aug 24 '20 at 18:52

Joni

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Thank you. I used File.separator because of this https://stackoverflow.com/a/2417515/6648326. Why do you recommend String.join(...) instead of StringBuilder.append(...) ? – MasterJoe Aug 25 '20 at 00:23
Btw, is there any code which can simply find game.exe file without having to mention directory structures which I did ? – MasterJoe Aug 25 '20 at 00:37
2

String.join is better than string append because in general less code = fewer bugs, and also you'll get performance improvements for free when standard library methods are improved. As for finding a file in a directory tree, you can use a FileVisitor https://docs.oracle.com/javase/tutorial/essential/io/walk.html – Joni Aug 25 '20 at 01:02

WJS · Answer 2 · 2020-08-24T19:45:00.607

String[] leafs = { "games", "game.exe" };
String path = makePath("user.dir", File.separator, leafs);
// or
String path = makePath("user.dir", File.separator, "games", "game.exe");
System.out.println(path);
    
    
public static String makePath(String property,String separator, String... leafs) {
        return System.getProperty(property) + File.separator 
                + String.join(File.separator, leafs);
}

score 1 · Answer 3 · edited Aug 25 '20 at 06:39

1

You don't need a function, and once you use File or Path then File.separator should be rarely used. For example Path.of() is all you need:

Path path = Path.of(System.getProperty("user.dir"), "games", "game.exe");
System.out.println("path="+path);

Some examples use Paths.get() but that just calls Path.of(). Note that Paths.of() is for JDK11+, but Paths.get() is JDK7+.

edited Aug 25 '20 at 06:39

MasterJoe

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answered Aug 24 '20 at 19:14

DuncG

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Forgot to add:- `Paths.of()` is for JDK11+, but `Paths.get()` is JDK7+ – DuncG Aug 24 '20 at 19:21

Shorthand to create a path in Java?

3 Answers3