Check Argument Precondition
Google Guava is a java library with lot of utilities and reusable components.
This requires the library guava-10.0.jar to be in classpath.
The following example shows using Preconditions.checkArgument() API.
It throws IllegalArgumentException if the given expression evaluates to false.
package com.bethecoder.tutorials.guava.base_tests; import com.google.common.base.Preconditions; public class CheckArgPreTest { /** * @param args */ public static void main ( String [] args ) { //Throws IllegalArgumentException - if expression is false //Preconditions.checkArgument(expression, errorMessage) /** * Negative case */ try { Preconditions.checkArgument ( args.length == 2 , "This program requires 2 arguments, but found %s" , args.length ) ; } catch ( IllegalArgumentException e ) { System.out.println ( e ) ; } /** * Positive case */ args = new String [] { "ONE" , "TWO" } ; Preconditions.checkArgument ( args.length == 2 , "This prog requires 2 arguments : %s" , args.length ) ; System.out.println ( "Thanks for providing valid input" ) ; } }
java.lang.IllegalArgumentException: This program requires 2 arguments, but found 0
Thanks for providing valid input
