Using variables outside of an if-statement

Question

I\'m not entirely sure if this is possible in Java, but how would I use a string declared in an if-statement outside of the if-statement it was declared in?

Answer 1

You need to distinguish between a variable declaration and assignment.

String foo;                     // declaration of the variable "foo"
foo = "something";              // variable assignment

String bar = "something else";  // declaration + assignment on the same line

If you try to use a declared variable without assigned value, like :

String foo;

if ("something".equals(foo)) {...}

you will get a compilation error as the variable is not assigned anything, as it is only declared.

In your case, you declare the variable inside a conditional block

if (someCondition) {
   String foo;
   foo = "foo";
}

if (foo.equals("something")) { ... }

so it is only "visible" inside that block. You need to move that declaration outside and assign it a value somehow, or else you will get conditional assignment compilation error. One example would be to use an else block :

String foo;

if (someCondition) { 
   foo = "foo";
} else {
   foo = null;
}

or assign a default value (null?) on declaration

String foo = null;

if (someCondition) {
   foo = "foo";
}