Java: Getting a variable name from a string

Question

I have some variables defined like this.

public final static String pDrive = "\\\\fs-innova1\\projects\\";
public final static String hDrive = "\\\\fs-innova1\\hr-department\\";
public final static String iDrive = "\\\\fs-innova1\\innova\\";

Then later in my program I have a string that says "p:\blah\blah\blah" I would like to look at the first char in that string and call the variable like Char(0)+"Drive

Jon Skeet · Accepted Answer · 2013-10-30 17:44:23Z

3

You should use a Map<String, String> instead:

private static final Map<String, String> DRIVE_MAPPINGS = new HashMap<>();

static {
    DRIVE_MAPPINGS.put("p", "\\\\fs-innova1\\projects\\");
    DRIVE_MAPPINGS.put("h", "\\\\fs-innova1\\hr-department\\");
    DRIVE_MAPPINGS.put("i", "\\\\fs-innova1\\innova\\");
}

Then use

String mapping = DRIVE_MAPPINGS.get(input.substring(0, 1));

(Alternatively, if you're really only ever going to want the key to be a single character, use a Map<Character, String> - it's the same idea.)

I would personally create an immutable map using Guava, but again the principle is the same - that would just make it obvious that you weren't going to change the contents of the map after construction.

edited Oct 30, 2013 at 17:44

answered Oct 30, 2013 at 17:33

Jon Skeet

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4 Comments

TC1 Over a year ago

Nitpicking, but Java 6 EOL was Feb '13, might as well promote using the diamond notation. :)

n1r3 Over a year ago

Well, I agree about Guava, but if it's not on the classpath, Collections.unmodifiableMap() would already be a good thing.

Jon Skeet Over a year ago

@TC1: Done here as it lets me get it all on one line - but I think a lot of Java coders are still on 6 (or even 5).

TC1 Over a year ago

@JonSkeet I know they are, I've seen 4 still in production, but of all the places, I think SO is on the top of the list to push knowledge of new features, especially since these make it more readable. :)

user1633277 · Accepted Answer · 2013-10-30 17:56:50Z

0

It is impossible to name variables at runtime. Your best bet is to use a map.

answered Oct 30, 2013 at 17:56

user1633277

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