tl  tr
  Home | Tutorials | Articles | Videos | Products | Tools | Search
Open Source | Tag Cloud | Follow Us | Bookmark | Contact   
 
 Tools and Libs > Google Guava > Basic > Check Argument Precondition

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.

File Name  :  
com/bethecoder/tutorials/guava/base_tests/CheckArgPreTest.java 
Author  :  Sudhakar KV
Email  :  kvenkatasudhakar@gmail.com
   
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");
  }

}
   

It gives the following output,
java.lang.IllegalArgumentException: This program requires 2 arguments, but found 0
Thanks for providing valid input


                    Print

   



Books Recommendation

 
 
bl  br