Eclipse tip : work around for the < argument

-
This post is a quick tip on Eclipse usage. Suppose you are running a java application that reads in a file whose name is supplied at the command line with the < operator. This idiom is used in Algorithms Fourth Edition by Robert Sedgewick and Kevin Wayne.
Example : java TopM 5 < tinyBatch.txt

The code to process the data in tinyBatch.txt is :
while (StdIn.hasNextLine()) {

}

The problem comes when you run the programs in Eclipse or in the Eclipse-based STS.
You can specify command line arguments via Right Click --> Properties --> Run/Debug Settings --> Edit -> Arguments -> Program Arguments. However, if you give < as a command line argument, the program waits for input, which you have to paste from your file into the console. This is not clean.

Fortunately there is a work around. You setIn the command line argument and your file processing code works properly. Here's how you do it:

import java.io.FileInputStream;
import java.io.FileNotFoundException;
try {
    System.setIn(new FileInputStream(args[1]));
}
catch (FileNotFoundException e) {
    e.printStackTrace();
}

Now you just give the filename as argument without the <.That is, java TopM 5 tinyBatch.txt
while (StdIn.hasNextLine()) {
works as usual.

Comments

Post a Comment

Popular posts from this blog

Mentoring Trainees In Java

-
Image
Every year we at 4S have a certain intake of trainees. They are asked to do a Java EE course at a training institute during their vacation before they join the company. The students do go to training institutes and come back with certificates. But when asked practical questions, we get blank faces. Despite whatever reputation and revenue they have, the Ameerpet training institutes just cover theory in classroom sessions. In fact, students are not even made aware of simple things like where to put the app files or the war file in the Tomcat container. This happened with the last year’s batch of management trainees too.
Read more

27th

-
Image
Wedding anniversaries of the past usually consisted of travelling somewhere, fine dining, or even ordering in favourite dishes, usually Biryani. There was this one year where we relished a movie followed by a romantic dinner. This time, we didn’t plan anything. However, the day before, I saw a Facebook post by Sarita Agarwal showcasing different menu items at her Gachibowli outlet. Sarita was one of the Sunrisers Hyderabad fandom cohorts with whom who I shared cricketing emotions. Up when SRH did well, down when they did not. Sharing views and exchanging notes after every game was like a decadent dessert after dinner. More on the IPL experience in a separate post. In jest, I asked Sarita whether Facebook friends are entitled to discounts? She replied, yes, why not. The allure of a discounted offer is truly irresistible. When you get something at a price lesser than standard retail, the feeling of accomplishment is heavenly. So, the decision was made. House of Truly, it would be on Sa
Read more

Fetching Blogger Posts With Python

-
As mentioned in a previous post, I am working through two chapters, 7 and 8 of Matthew Russel’s eminently fun-filled book Mining The Social Web (MTSW). As a first step, I took a go at blogger posts. Example 8-1, blogs_and_nlp__get_feed.py gets blog posts from their feeds and saves them in json format.
Read more