can someone pls explain output od this code

Question

public class vjezbe {
public static void main(String [] args){
String a="sad";
String b="SAD".toLowerCase();
if(a==b){
System.out.println(true);

}else{
System.out.println(false);
}

System.out.println(b);
}
}

Answer 1

Use .equals() method

Answer 2

public class vjezbe {
public static void main(String [] args){
String a="sad";
String b="SAD".toLowerCase();
if(a.equals(b)){
System.out.println(true);

}else{
System.out.println(false);
}

System.out.println(b);
}
}

Answer 3

aaa so I cant use == here?
thanks for clue i google more about this