Which “if” construct is faster – statement or ternary operator?

by

There’s only one type of “if” statement there. The other is a conditional expression. As to which will perform better: they could compile to the same bytecode, and I would expect them to behave identically – or so close that you definitely wouldn’t want to choose one over the other in terms of performance.

Sometimes an if statement will be more readable, sometimes the conditional operator will be more readable. In particular, I would recommend using the conditional operator when the two operands are simple and side-effect-free, whereas if the main purpose of the two branches is their side-effects, I’d probably use an if statement.

Here’s a sample program and bytecode:

public class Test {
    public static void main(String[] args) {
        int x;
        if (args.length > 0) {
            x = 1;
        } else {
            x = 2;
        }
    }

    public static void main2(String[] args) {
        int x = (args.length > 0) ? 1 : 2;
    }
}

Bytecode decompiled with javap -c Test:

public class Test extends java.lang.Object {
  public Test();
    Code:
       0: aload_0
       1: invokespecial #1
       4: return

  public static void main(java.lang.String[]
    Code:
       0: aload_0
       1: arraylength
       2: ifle          10
       5: iconst_1
       6: istore_1
       7: goto          12
      10: iconst_2
      11: istore_1
      12: return

  public static void main2(java.lang.String[
    Code:
       0: aload_0
       1: arraylength
       2: ifle          9
       5: iconst_1
       6: goto          10
       9: iconst_2
      10: istore_1
      11: return
}

As you can see, there is a slight difference in bytecode here – whether the istore_1 occurs within the brance or not (unlike my previous hugely-flawed attempt 🙂 but I would be very surprised if the JITter ended up with different native code.

More Related Contents:

  1. Performance of java if-else with return statement [duplicate]
  2. What is the relative performance difference of if/else versus switch statement in Java?
  3. Are Java static calls more or less expensive than non-static calls?
  4. Multiple statement is passed in IF condition using OR, how to find which statement is true?
  5. Why is my if statement an error?
  6. Semicolon at end of ‘if’ statement
  7. When to use StringBuilder in Java [duplicate]
  8. The performance impact of using instanceof in Java
  9. What is the Cost of Calling array.length
  10. Error: ‘else’ without ‘if’
  11. Performance of Java matrix math libraries? [closed]
  12. Fastest way to iterate over all the chars in a String
  13. How do I speed up the gwt compiler?
  14. Performance of StringTokenizer class vs. String.split method in Java
  15. Is there any performance reason to declare method parameters final in Java?
  16. Why is System.out.println so slow?
  17. Why doesn’t my compare work between char and int in Java?
  18. Android RecyclerView Scrolling Performance
  19. Java HashMap performance optimization / alternative
  20. Does variable = null set it for garbage collection
  21. Fastest way to iterate an Array in Java: loop variable vs enhanced for statement [duplicate]
  22. JTable Calls Custom Cell Renderer Method… Continuously
  23. Fastest way to sum integers in text file
  24. Java try/catch performance, is it recommended to keep what is inside the try clause to a minimum?
  25. fastest (low latency) method for Inter Process Communication between Java and C/C++
  26. What is the best macro-benchmarking tool / framework to measure a single-threaded complex algorithm in Java? [closed]
  27. compareTo with primitives -> Integer / int
  28. Writing image to servlet response with best performance
  29. Java Collections and Garbage Collector
  30. Why is the 64bit JVM faster than the 32bit one?

Leave a Comment