Extract Method

When the Extract Method refactoring is invoked, IntelliJ IDEA analyses the selected block of code and detects variables that are the input for the selected code fragment and the variables that are output for it.

If there is exactly one output variable, it is used as a return value for the extracted method. In case there are multiple output variables, the Extract Method refactoring may not be applied, and the error message appears.

There are several workarounds to allow Extract Method work in this case. For example, you may introduce a special data-class that contains all output values.

• Example
• Extracting a method

public void method() {
    int a=1;
    int b=2;
    int c=a+b;
    int d=a+c;
}
    

public void method() {
    int a=1;
    int b=2;
    int c=add(a,b);
    int d=add(a,c);
}
    ...
private int add(int a, int b) {
    return a+b;
}
    

public ArrayList method() {
    String[] strings = {"a","b","c"};
    ArrayList list = new ArrayList();
    for (int i=0; i < strings.length; i++)
        {list.add(strings[i]);}
    return list;
}
    

public ArrayList method() {
    String[] strings = {"a","ab","abc"};
    ArrayList list=add(strings);
    return list;
}

private ArrayList add(String[] strings) {
    ArrayList list = new ArrayList();
    for (int i=0; i < strings.length; i++)
        {list.add(strings[i]);}
    return list;
}