Question

For better readability of a lengthy method, I’d like to replace a repeatedly used block of code (only assignments) with a method. I therefore selected the block of code and ran Eclipse’s Extract Method feature, but that failed with this error:

Ambiguous return value: Selected block containsmore than one assignment to local variables. Affacted variables are:

int foo
double[] bar

How can I fix this? It should be a simple void method doing a couple of assignments, I’m not sure what Eclipse (3.6.2) complains about.

Answer 1

Eclipse wants all variables that are used as arguments and return one or no variable that was modified within the extracted block.

You issue is a construct like

void f2() {
        int a,b;
        int foo=0;                           // selection start
        double[] bar = new double[10];
        for ( int i = 0 ; i < bar.length ; i++ ) {
            bar[i] = foo;
        }
        foo = 0;                             // selection end

        a = foo;
        b = (int) bar[0];
    }

Since both variables (foo,bar) are needed in further statements they can’t be returned as one value.
You could return a class containing foo and bar.

Declareing them as member variables works

public class Refactor {
    int foo ;
    double[] bar; 

    void f2() {
        for ( int i = 0 ; i < bar.length ; i++ ) {        // selection start
            bar[i] = foo;
        }
        foo = 0;                                          // selection end
    }
}

as well as this:

void f2() {
        int foo=0;                                  // selection start
        double[] bar = new double[10];
        for ( int i = 0 ; i < bar.length ; i++ ) {
            bar[i] = foo;
        }
        foo = 0;                                    // selection end
    }