Handling Exceptions and Debugging - Beginning Java Programming: The Object-Oriented Approach - page 192

scan.close();
}
}
}
Note that in order for the scan object to be accessible in both the try and finally blocks, it must
be declared outside either block. Now look at the try‐with‐resources block.
import java.text.DecimalFormat;
import java.util.Scanner;
public class Resources {
public static void main(String[] args) {
try (Scanner scan = new Scanner(System.in)){
System.out.print("Enter the loan amount: ");
double principle = scan.nextDouble();
System.out.print("Enter the interest rate: ");
double rate = scan.nextDouble();
System.out.print("Enter the loan term (in years): ");
double years = scan.nextInt();
double interest = principle*rate*years;
double total = principle + interest;
double payment = total/years/12;
DecimalFormat df = new DecimalFormat ("0.##");
System.out.println("Monthly payment: $"
+ df.format(payment));
} catch (Exception exc){
System.out.println(exc);
}
}
}
By adding the declaration and initialization directly to the try block, the resource will automatically
be closed no matter how the rest of the try block completes (with or without exception). Imagine
you come back to this code later and decide to change the System.in scanner to some other user
interface. Simply by changing the resource in the try clause, you are assured that it will be closed
correctly. You can also declare more than one resource, if necessary, simply by separating the
resources with a semicolon. You will see many more examples of this in Chapter 8, where the differ-
ent tools available for reading and writing will be explained fully.
In Java, there are two types of exceptions: checked and unchecked. Specifically, the Exception class
has a subclass called runtime exceptions. Runtime exceptions and any subclasses are unchecked,
while all other types of exceptions are checked. Java requires that checked exceptions be handled,
and you will see this indicated with an error alert in Eclipse or other compilers. Eclipse offers two
possible solutions: declare that the method might throw a particular type of exception or enclose
particular statements in a try/catch designed to handle those exceptions. If you simply add a
throws declaration, you are not handling the exception in any way; you are simply alerting any-
one who might call this method that an exception is possible. In order to handle the exceptions,
you should use a try/catch block. In your main method, the try/catch solution is certainly