The String class
Be aware of where an object refers.
String a = "Bob";
String b = "Jack";
System.out.println(a);
a = b;
System.out.println(b);
＜Result＞
Bob
Jack
String objects are immutable
＜Sample＞
String a = "Bob";
a.concat(" Cruise");
System.out.println(a);
＜Result＞
Bob
You cannot change the String object ‘a’ refers to.
＜Sample＞
String a = "Bob";
a = a.concat(" Cruise");
System.out.println(a);
A new object is substituted for what ‘a’ referred to.
＜Result＞
Bob Cruise
_________
The StringBuilder class
The StringBuilder class is similar to the StringBuffer class, but the StringBuilder class is faster than the StringBuffer class in almost every aspect
When you connect strings it is better to use the StringBuilder class.
＜Sample＞
StringBuilder a = new StringBuilder("Bob");
a.append(" Cruise");
System.out.println(a);
＜Result＞
Bob Cruise
You can append, replace, insert another string to the StringBuilder object ‘a’ refers to.
