Strings are immutable?

Q4-8. What is the output of the following code?

class EJavaGuruString2 {

public static void main(String args[]) {

String ejg = "game".replace('a', 'Z').trim().concat("Aa");

ejg.substring(0, 2);

System.out.println(ejg);

}

}

a gZmeAZ

b gZmeAa

c gZm

d gZ

e game

Answer: b

Q4-9. What is the output of the following code?

class EJavaGuruString2 {

public static void main(String args[]) {

String ejg = "game";

ejg.replace('a', 'Z').trim().concat("Aa");

ejg.substring(0, 2);

System.out.println(ejg);

}

}

a gZmeAZ

b gZmeAa

c gZm

d gZ

e game

Answer: e

WHY? the first one when u use methods such as replace, it changes the string, but the second example still uses replace but nowwww it saying that stringes are immutable!