Concatenation

Any two strings can be concatenated by using the + operator.

String he = "he";
String llo = "llo";

String hello = he + llo;

System.out.println(hello);

This will make a new String where the characters from the first one all appear followed by the characters in the second one.

If you try to concatenate a String to something that is not a String, like an int or a double, then the result will be a new String with the characters from the "string representation" of that other thing.

int numberOfApples = 5;
double dollahs = 1.52;

String message = "I have " + numberOfApples + 
    " apples and $" + dollahs + " in my pocket.";

System.out.println(message);