According to Sun, we can use assertion to test our assumption
about programs. That means it validates our program!
In another words we can say that assertions ensures the program validity by catching exceptions and logical errors. They can be stated as comments to guide the programmer. Assertions are of two types:
In another words we can say that assertions ensures the program validity by catching exceptions and logical errors. They can be stated as comments to guide the programmer. Assertions are of two types:
1.
Preconditions:
Preconditions are the assertions which invokes when a method is
invoked.
2.
Postconditions:
Postconditions are the
assertions which invokes after a method finishes.
Where
to use Assertions?
We can use assertions in java to make it more understanding and user friendly, because assertions can be used while defining preconditions and post conditions of the program.
We can use assertions in java to make it more understanding and user friendly, because assertions can be used while defining preconditions and post conditions of the program.
Example
of AssertionExample.java
import java.util.Scanner;
public class AssertionExample
{
public static
void main( String args[] )
{
Scanner
scanner = new Scanner( System.in );
System.out.print( "Enter a number between 0 and 20: " );
int value =
scanner.nextInt();
assert(
value >= 0 && value <= 20 ):
"Invalid number: " + value;
System.out.printf( "You have entered %d\n", value );
}
}
Before running above example
enable the assertion at your environment
with following command.
java -ea AssertionExample
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