AVAJAVA Web Tutorials

The NumberFormat class allows us to format numbers such as doubles. The NumberFormatTest class displays several of the ways that doubles can be formatted with NumberFormat.

NumberFormatTest.java

package test;

import java.text.NumberFormat;

public class NumberFormatTest {

	public static void main(String[] args) throws Exception {

		NumberFormat format1 = NumberFormat.getInstance();
		displayNumbers("default", format1);

		NumberFormat format2 = NumberFormat.getInstance();
		format2.setMinimumFractionDigits(2);
		format2.setMaximumFractionDigits(4);
		displayNumbers("min fraction digits 2, max fraction digits 4", format2);

		NumberFormat format3 = NumberFormat.getInstance();
		format3.setMinimumIntegerDigits(6);
		displayNumbers("min integer digits 6", format3);

		NumberFormat format4 = NumberFormat.getInstance();
		format4.setMaximumIntegerDigits(5);
		displayNumbers("max integer digits 5", format4);

		NumberFormat format5 = NumberFormat.getInstance();
		format5.setGroupingUsed(false);
		displayNumbers("grouping off", format5);

	}

	public static void displayNumbers(String whichFormat, NumberFormat numberFormat) {
		System.out.println("Format:" + whichFormat);
		for (int i = 0; i <= 10; i++) {
			double num = Math.PI * Math.pow(i, i) * i;
			System.out.print("  formatted:" + numberFormat.format(num));
			System.out.println(" | unformatted:" + num);
		}
		System.out.println();
	}

}

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