Java Reference
In-Depth Information
The try Statement
A try statement is a block of code that contains one or more statements that may throw
an exception. A try statement can be followed by one or more catch clauses , also called
exception handlers. Figure 3.10 shows the syntax of a try statement.
The syntax of a try statement
FIGURE 3.10
If an exception is thrown in a try
statement, the catch clauses
attempt to catch it.
The try keyword
try {
The identifier refers to
the caught exception
object.
//The try block is also referred to
//as protected code
} catch ( exception_type identifier ) {
//exception handler
Curly braces are
required.
}
The type of
exception you are
trying to catch
The catch keyword
A try statement can declare any number of catch clauses. A catch clause must have
exactly one parameter: the data type of the exception trying to be caught. If an exception
is thrown within a try block, the JVM searches for a handler by checking the exception
types of its catch clauses in the order they appear. If the exception type of a catch clause
matches the data type of the thrown exception, fl ow of control jumps to that catch block
and the catch 's identifi er receives a copy of the reference to the exception object (similar to
an argument copied into a method parameter).
For example, the following try statement catches the ArithmeticException thrown in
method3 of the ExceptionDemo class from the previous section. See if you can determine the
output of running main in ExceptionDemo if method3 is modifi ed as follows:
12. public void method3() {
13. System.out.println(“Inside method3”);
14. int x = 5, y = 0;
15. try {
16. int z = x/y; //throws an ArithmeticException
17. System.out.println(“z = “ + z);
18. }catch(ArithmeticException e) {
19. System.out.println(“Something went wrong: “
20. + e.getMessage());
21. }
23. }
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