The method createOperate cannot be declared static; static methods can only be declared in a static or top level type

Question

public class Welcome {
    public class OperationFactory {

        public static Operation createOperate(String operate) {
            Operation operation = null;
            if("+".equalsIgnoreCase(operate)) {
                operation = new OperationAdd();
            }else if("-".equalsIgnoreCase(operate)) {
                operation = new OperationSub();
            }else if("*".equalsIgnoreCase(operate)) {
                operation = new OperationMul();
            }else {
                operation = new OperationDiv();
            }
            return operation;
        }
    }
}

The question is that:The method createOperate cannot be declared static; static methods can only be declared in a static or top level type I do not know how to resolve. Thank you

Answer 1

As the error message clearly states, you have 3 options :

1. change the createOperate method to be non-static
2. change the OperationFactory class to be static
3. move the static method createOperate to the enclosing Welcome class