Java Reference
In-Depth Information
You must always do things like this when dealing with command-line arguments.
Otherwise, your programs crash with ArrayIndexOutOfBoundsException errors when-
ever the user supplies fewer command-line arguments than you were expecting.
If at least one argument is passed, the for loop iterates through all the strings stored in
the arguments array (lines 6-8).
Because all command-line arguments are passed to a Java application as String objects,
you must convert them to numeric values before using them in any mathematical expres-
sions. The parseInt() class method of the Integer class takes a String object as input
and returns an int (line 7).
If you can run Java classes on your system with a command line, type the following:
java Averager 1 4 13
You should see the following output:
Sum is: 18
Average is: 6.0
Creating Methods with the Same Name,
Different Arguments
When you work with Java's class library, you often encounter classes that have numerous
methods with the same name.
Two things differentiate methods with the same name:
The number of arguments they take
n
The data type or objects of each argument
n
These two things are part of a method's signature. Using several methods with the same
name and different signatures is called overloading .
Method overloading can eliminate the need for entirely different methods that do essen-
tially the same thing. Overloading also makes it possible for methods to behave differ-
ently based on the arguments they receive.
When you call a method in an object, Java matches the method name and arguments to
choose which method definition to execute.
To create an overloaded method, you create different method definitions in a class, each
with the same name but different argument lists. The difference can be the number, the
 
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