format a number in java

/**
 * @author lautturi.com 
 * Java example: format a number in java
 */

import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.util.*;

public class Lautturi {
	public static void main(String args[]) {
		double pi = 3.14159;
		System.out.println(pi);

		BigDecimal bd = new BigDecimal(pi);
		int decimalPlaces = 2;
		bd = bd.setScale(decimalPlaces, BigDecimal.ROUND_HALF_UP);
		double newPi = bd.doubleValue();
		System.out.println(newPi);
		
		String strPI = String.format("%.2f",pi);
		System.out.println(strPI);
		
		System.out.printf("%.2f", pi);
		System.out.println();
		
		DecimalFormat df = new DecimalFormat("#.00");
		String dfPi = df.format(pi); 
		System.out.println(dfPi);
	}
}

output:

3.14159
3.14
3.14
3.14
3.14