Retrieving the value of a concatenated variable within a Java FOR loop

Question

I have been using this "logic" in C++ and VB with success, but am tied up in Java... Simply put,

public void DataProviderExample(String user, String pwd, String no_of_links,
        String link1, String link2, String link3) {

for (int i=1;i<=no_of_links;i++) {
         String link = "link"+i;
         System.out.println(link);
}

Now, if the variables link1, link2 and link3 have a value of "X", "Y" and "Z" respectively, upon running this program, I get the following output -

link1
link2
link3

What I want is -

X
Y
Z

Any ideas?

I'm guessing he doesn't actually print the string "link" + i, but does some sort of eval(link) which gets the value of the variable with the name defined in the variable link. The code above is the closest he came to that in Java. — Andrei Fierbinteanu
– Andrei Fierbinteanu, Commented May 24, 2010 at 20:14

Péter Török · Accepted Answer · 2010-05-24 19:50:51Z

5

You could use varargs:

public void DataProviderExample(String user, String pwd, String... links) {

for (String link : links) {
         System.out.println(link);
    }
}

...
DataProviderExample("user1", "password1", "X", "Y", "Z");
DataProviderExample("user2", "password2", "Q");

This way you can pass in the desired number of links, and the runtime automagically puts these into an array, which you can iterate over with a foreach loop.

With a plain array, calls would be more cumbersome (unless you already have the links in an array, of course):

public void DataProviderExample(String user, String pwd, String[] links) { ... }

DataProviderExample("user1", "password1", new String[] {"X", "Y", "Z"});

edited May 24, 2010 at 19:50

answered May 24, 2010 at 19:42

Péter Török

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1 Comment

Leni Kirilov Over a year ago

+1 - I recommend this approach. What you describe that is valid for VB can be made with Reflection - you want to dynamically form names of variables.

Jan K. · Accepted Answer · 2010-05-24 19:42:02Z

3

why aren't you using an array instead?

answered May 24, 2010 at 19:42

Jan K.

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Comments

Hank Gay · Accepted Answer · 2010-05-24 19:44:15Z

0

As @Jan Kuboschek points out, you should be using an array. Failing that, check out reflection.

answered May 24, 2010 at 19:44

Hank Gay

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rs79 · Accepted Answer · 2010-05-25 13:32:53Z

0

I appreciate the answer. I am attempting to retrieve the parameters for the function from an external Excel file. Trying both the approaches you describe, I encounter a "java.lang.IllegalArgumentException: argument type mismatch" error. Any ideas why? :)

Declaration: DataProviderExample(String user,String pwd,String...links) {...} Calls: DataProviderExample("user1","pwd1","X","Y","Z"); DataProviderExample("user2","pwd2","X","Y");

I also tried the "array" approach and got the same argument mismatch error. Declaration: DataProviderExample(String user,String pwd,String[] links) {...} Calls: DataProviderExample("user1","pwd1",{"X","Y","Z"}); DataProviderExample("user2","pwd2",{"X","Y"});

Again, the parameters, user1, user2, pwd1, pwd2 and the links array are being retrieved from an Excel file.

Thanks.

answered May 25, 2010 at 13:32

rs79

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1 Comment

rs79 Over a year ago

Not the most graceful of workarounds...but I passed the dynamic string variable as a single string to the function and simply spilt it into an array based on a "," delimiter...

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