Four ways to format decimals and retain two decimals in Java

Formatting decimals and retaining two decimals in Java can be achieved in the following ways:

1. Use the DecimalFormat class

import ;
import ;

public class DecimalFormatExample {
    public static void main(String[] args) {
        double number = 3.1415;

        DecimalFormat df = new DecimalFormat("0.00");
        (RoundingMode.HALF_UP); // Set rounding mode
        String formatted = (number);
        (formatted); // Output: 3.14    }
}

illustrate:

Mode "0.00": Forced to retain two decimal places, not enough to make up for zeros (for example, 2.5 formatted to 2.50).

RoundingMode.HALF_UP: Rounding rule (3.145 → 3.15).

2. Use ()

public class StringFormatExample {
    public static void main(String[] args) {
        double number = 3.1415;

        String formatted = ("%.2f", number);
        (formatted); // Output: 3.14    }
}

illustrate:

Format string "%.2f": Automatically retain two decimal places, and the zero is not enough to be filled.

Locale problem: The system locale setting is used by default. If you need to fix the decimal symbol to ., you can specify:

String formatted = (, "%.2f", number);

3. Use BigDecimal (high precision calculation)

import ;
import ;

public class BigDecimalExample {
    public static void main(String[] args) {
        double number = 3.145;

        BigDecimal bd = (number);
        bd = (2, RoundingMode.HALF_UP);

        String formatted = ();
        (formatted); // Output: 3.15    }
}

illustrate:

(number): Avoid accuracy problems caused by direct use of new BigDecimal(double).

setScale(2, RoundingMode.HALF_UP): Sets the decimal places and rounding modes.

4. Use NumberFormat (localized format)

import ;
import ;

public class NumberFormatExample {
    public static void main(String[] args) {
        double number = 1234.567;

        NumberFormat nf = ();
        (2);
        (2);

        String formatted = (number);
        (formatted); // Output: 1,234.57 (including the thousandths delimiter)    }
}

illustrate:

setMinimumFractionDigits(2) and setMaximumFractionDigits(2): Fixed two decimal places.

: Specify the decimal symbol as . and the thousandth part is ,.

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