Using local variables or global attributes

Question

it's been five years now since I learned programming.
But I still have a pretty basic question that isn't answerred yet ...
I'll try to explain it with an example
     //*attributes*
     private int a, b, c;
     private int result
     a =1;
     b =2;
     c=3;
     //first option
     calculate1();
     System.out.println("the result is : " + result);
     //second option
     calculate2(a,b,c);
     System.out.println("the result is : " + result);
     //third option
     result = calculate3();
     System.out.println("the result is : " + result);
     //fourth option
     result = calculate4(a,b,c);
     System.out.println("the result is : " + result);
     private void calculate1(){
          result = a+b+c;
     private void calculate2(int a, int b, int c){
          result = a + b + c;
     private int calculate3(){
          return a+b+c;
     private int calculate4(int a, int b, int c){
          return a+ b + c;
     }what's the best, and why?

Answer 1

Regarding performance:
I tested your example with the code below. I run every test case 10 times: These are the results:
calculate1 = 7567 ms
calculate2 = 8046 ms
calculate3 = 7609 ms
calculate4 = 8047 ms
So, the variants with method parameters are slower. That’s clear, because we have to push and pop the variables to/from stack. I think the ‘huge’ difference between calculate1 and calculate2 results from the unpurified test (Garbage Collector activities, System activities, …).
Regarding style:
It’s up to you, if you like to use your attributes directly or method parameters. That’s OOP :)
As far as I’m concerned:
Your attributes are private. So, within an object I would try to use the attributes directly as often as possible. That’s the reason why I would use calculate1.
Cheers,
Chris
public class TestMe {
     private int a = 1, b = 2, c = 3;
     private int result;
     private int n = 1000000000;
     public void testCalculate1() {
          long t0 = System.currentTimeMillis();
          for (int i = 0; i < n; i++) {
               calculate1();
          long t1 = System.currentTimeMillis();
          System.out.println((t1 - t0));
     public void testCalculate2() {
          long t0 = System.currentTimeMillis();
          for (int i = 0; i < n; i++) {
               calculate2(a, b, c);
          long t1 = System.currentTimeMillis();
          System.out.println(t1 - t0);
     public void testCalculate3() {
          long t0 = System.currentTimeMillis();
          for (int i = 0; i < n; i++) {
               result = calculate3();
          long t1 = System.currentTimeMillis();
          System.out.println(t1 - t0);
     public void testCalculate4() {
          long t0 = System.currentTimeMillis();
          for (int i = 0; i < n; i++) {
               result = calculate4(a, b, c);
          long t1 = System.currentTimeMillis();
          System.out.println(t1 - t0);
     private void calculate1() {
          result = a + b + c;
     private void calculate2(int a, int b, int c) {
          result = a + b + c;
     private int calculate3() {
          return a + b + c;
     private int calculate4(int a, int b, int c) {
          return a + b + c;
     public static void main(String args[]) {
          TestMe t = new TestMe();
          // t.testCalculateX();
}