Execute a method corresponding to a received String

Question

I'm new to Java and I want to execute a method corresponding to a String I receive. In Python I would just do this

myString = "create"
options = {
    "create": self.create,
    "delete": self.delete,
    "list_jobs": self.list_jobs
}
options[myString]()

Is this possible in Java?

Take a look at the Java Reflection tutorial at Oracle: http://docs.oracle.com/javase/tutorial/reflect/ — Edwin Torres, Jun 06 '14 at 14:49
http://stackoverflow.com/questions/160970/how-do-i-invoke-a-java-method-when-given-the-method-name-as-a-string — , Jun 06 '14 at 14:49
It is possible. You have to refine the words you use in your queries when doing your research on the net — Luiggi Mendoza, Jun 06 '14 at 14:52

score 0 · Answer 1 · answered Jun 06 '14 at 14:50

0

Java doesn't have anything like that, but you can use a switch.

switch (myString) {

    case "create":
        self.create;
        break;
    case "delete":
        self.delete;
        break;
    case "list_jobs":
        self.list_jobs;
        break;
}

Note that you probably should use more complicated object oriented concepts, but for simple programs this works fine.

answered Jun 06 '14 at 14:50

Anubian Noob

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This is fine for a specific set of methods and a single class. For a more generic (and proper) approach, use reflection. – Luiggi Mendoza Jun 06 '14 at 14:51
Hmm yeah... It would work for his case though... – Anubian Noob Jun 06 '14 at 14:52
We don't know if this is just a sample of the real problem... – Luiggi Mendoza Jun 06 '14 at 14:52

Solomon Slow · Answer 2 · 2014-06-06T14:57:01.563

I would use a Map<String, Runnable>.

Map<String, Runnable> commandTable = new HashMap<String, Runnable>();

static void initCommandTable() {
    commandTable.add("foo", new Runnable() { 
        @Override
        public void run() {
             //implement foo command
             ...
        });

    commandTable.add("bar", new Runnable() { 
        @Override
        public void run() {
             //implement bar command
             ...
        });

    ...
}

void doCommand(String command) {
    commandTable.get(command).run();
}

Yeah, Java is a lot more verbose than Python. But we knew that already.

Execute a method corresponding to a received String

2 Answers2