The class java.lang.String is unusual because an operator is defined in the language specifically for the concatenation of the values of two objects of this class:

String tFirstName = new String("James");
String tSurname = new String("Gosling");
String tName = tFirstName + tSurname;

The variable tName now points to a string object containing the string "JamesGosling". Perhaps that is not what we were after. So use this instead:

String tName = tFirstName + " " + tSurname;

The string concatenation operator is very flexible in that it will convert any operand (that is permitted) into a string. Here is an example:

Point tFirstPoint = new Point(100, 200);
String tLine = "The point has the value " + tFirstPoint;
System.out.println(tLine);

This will output:

The point has the value java.awt.Point[x=100,y=200]

If you have a long string literal, the string concatenation operator can be used to help in the layout of the text. For example, the statement:

System.out.println("Lister glared at Rimmer.  \"You really are a smeghead\", he said.");

can instead be written as:

System.out.println("Lister glared at Rimmer." +
                   "  \"You really are a smeghead\", he said.");