Sams Teach Yourself Java™ in 24 Hours (Covering Java 7 and Android)

ptg7068951

Using Other Variables with Strings 69

int length = 121;
char rating = ‘R’;
System.out.println(“Running time: “ + length + “ minutes”);
System.out.println(“Rated “+ rating);

This code will be displayed as the following:

Running time: 121 minutes
Rated R

This example displays a unique facet about how the +operator works with
strings. It can cause variables that are not strings to be treated just like
strings when they are displayed. The variable lengthis an integer set to the
value 121. It is displayed between the strings Running time:and minutes.
The System.out.println()statement is being asked to display a string
plus an integer, plus another string. This statement works because at least
one part of the group is a string. The Java language offers this functionality
to make displaying information easier.

One thing you might want to do with a string is paste something to it sev-
eral times, as in the following example:

String searchKeywords = “”;
searchKeywords = searchKeywords + “drama “;
searchKeywords = searchKeywords + “romance “;
searchKeywords = searchKeywords + “New Zealand”;

This code would resultin the searchKeywordsvariable being set to “drama
romance New Zealand”. The first line creates the searchKeywordsvariable
and sets it to be an empty string because there’s nothing between the dou-
ble quotation marks. The second line sets the searchKeywordsvariable
equal to its current string plus the string “drama” added to the end. The
next two lines add “romance” and “New Zealand” in the same way.

As you can see, when you are pasting more text at the end of a variable,
the name of the variable has to be listed twice. Java offers a shortcut to
simplify this process: the +=operator. The +=operator combines the func-
tions of the =and +operators. With strings, it is used to add something to
the end of an existing string. The searchKeywordsexample can be short-
ened by using +=, as shown in the following statements:

String searchKeywords = “”;
searchKeywords += “drama “;
searchKeywords += “romance “;
searchKeywords += “New Zealand”;

This code produces the same result: searchKeywordsis set to “drama
romance New Zealand”.