for循环内部的变量是局部的，我想将其公开

Question

if (a != 1 && solone == (int)solone && soltwo == (int)soltwo){
    // (lx+o)(mx+p)
    int h = (a*c);
    List<Integer> factors = new ArrayList<Integer>();
    for (int i = 1; i < Math.sqrt(h); i++) {
        if (h % i == 0)
            factors.add(i);
    }
    Integer result = null;
    for (int ii: factors) {
        if (b == ii + h/ii){
            result = ii;
            // ax^2+hiix+iix+c
    }
    int hii = h/ii;
    int gcd1 = Euclid.getGcd(a, hii);
    int gcd2 = Euclid.getGcd(ii, c);
    String Factored = FactoredForm.getFF(gcd1, gcd2, a, hii);
}

My String called Factored is one I need to use for printing later in my code. I can't use it because it doesn't recognize the variable outside of the for loop. How do I go about making it public? When i added public in front of the string, it said that only final is permitted? Also, I cannot simply move the extraneous code outside of the for loop because it all depends on the integer "ii" which is part of the loop. Help!

Answer 1

Do you really want this to be part of the state of an instance of the class? If so, declare it outside the method:

private string factored;

public void Whatever(...)
{
    factored = FactoredForm.getFF(gcd1, gcd2, a, hii);
}

I would advise you not to make it public. If you need to expose the value, do so via a property.

Think carefully about whether it really is logically part of the state of this class though. Also revisit naming conventions, as mentioned before.

Answer 2

public attribute is not related to a local variable but to an instance variable .

Inside the same function declarations follow two rules:

• the order of declaration : if a local variable hasn't been declared yet, then you can't use it.
• the scoping : if a variable has been declared inside a scope ( { ... } ) then you can't access it from outside the scope.

If you want to access the variable later in the code you should declare it before the loop:

String factored;
if (....) {
  ....
  ....
  factored = whatever;
}

System.out.println(factored);

or have it as an instance variable (meaningless, since it's a local that you need to print but whatever):

class FooBar
{
  String factored;

  void method() {
    ...
    ...
    if (...) {
      ...
      ...
      factored = whatever;
    }

    System.out.println(factored);
  }
}

or thirdly you can return the variable from the method and use it somewhere else:

class FooBar
{
  String method() {
    ...
    ...
    if (...) {
      ...
      ...
      return whatever;
    }

    return null;
  }

  void otherMethod() {
    String factored = method();
    System.out.println(factored);
  }

}