Java String Concatenation with + operator

Question

I got confused with the String concatenation.

String s1 = 20 + 30 + \"abc\" + (10 + 10);
String s2 = 20 + 30 + \"abc\" + 10 + 10;
System.out.println(s1);
Sys         


        

Answer 1

Also, to add to this topic, as the wrong part of the answer of Jonathan Schober tipped me off on a thing to keep in mind:

a+=something is not equal to a=a+ : the += evaluates the right side first, and only then adds it to the left side. So it has to be rewritten, it is equivalent to:

a=a+(something); //notice the parentheses!

Showing the difference

public class StringTest {
  public static void main(String... args){
    String a = "";
    a+=10+10+10;

    String b = ""+10+10+10;

    System.out.println("First string, with += : " + a);
    System.out.println("Second string, with simple =\"\" " + b);

  }
}