Formatting a Decimal Number to 2 Decimal Places in Java or JSP

I was looking around for the class to format a number to 2 decimal places while I was coding Java, or specifically JSP, and I found it.

First, you need to import the DecimalFormat class, so have this line at the top of your Java file:

import java.text.DecimalFormat;

Or if you’re running JSP:

<%@page import="java.text.DecimalFormat" %>

And here’s the actual code that does the magic:

double price = 10.59;
DecimalFormat priceFormatter = new DecimalFormat("$#0.00");
return priceFormatter.format(price);

That’s all there is to it! Simply change the Formatting string “$#0.00″ to anything you wish. The pound (#) sign simply means there can be optional digits there. The two zero’s (0) to the right of the decimal place means that it has only 2 decimal places, and will be replaced by 0s if you don’t have digits there. Te $ sign right at the start is something that I put in, because I wanted to display my prices in dollars ($).

So for example, you can also have the formatting string as “#0.00 seconds more” and it’ll show “2343.36 seconds more”.

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Running UNIX commands in your Java application

I was looking around for a method to run commands from the prompt automatically from within my Java application, and then I found it. Here’s the solution - and it works like a charm!

static void doExec1() throws IOException {

// use pipes and I/O redirection
// but without using a shell

Runtime runtime = Runtime.getRuntime();
runtime.exec(”ls | wc >out1″);
}

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Replace/remove character in a String

To replace all occurences of a given character :

String.replaceAll("n", ""); // Remove all n
String.replaceAll("n", "r"); // Replace n by r

To replace a character at a specified position :

public static String replaceCharAt(String s, int pos, char c) {
return s.substring(0,pos) + c + s.substring(pos+1);
}

To remove a character :

public static String removeChar(String s, char c) {
String r = "";
for (int i = 0; i < s.length(); i ++) {
if (s.charAt(i) != c) r += s.charAt(i);
}
return r;
}

To remove a character at a specified position:

public static String removeCharAt(String s, int pos) {
return s.substring(0,pos)+s.substring(pos+1);
}

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