Java格式化小数并保留两位小数的四种方法

import java.text.DecimalFormat;
import java.math.RoundingMode;

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

        DecimalFormat df = new DecimalFormat("0.00");
        df.setRoundingMode(RoundingMode.HALF_UP); // 设置四舍五入模式

        String formatted = df.format(number);
        System.out.println(formatted); // 输出：3.14
    }
}

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

        String formatted = String.format("%.2f", number);
        System.out.println(formatted); // 输出：3.14
    }
}

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

import java.math.BigDecimal;
import java.math.RoundingMode;

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

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

        String formatted = bd.toString();
        System.out.println(formatted); // 输出：3.15
    }
}

import java.text.NumberFormat;
import java.util.Locale;

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

        NumberFormat nf = NumberFormat.getInstance(Locale.US);
        nf.setMinimumFractionDigits(2);
        nf.setMaximumFractionDigits(2);

        String formatted = nf.format(number);
        System.out.println(formatted); // 输出：1,234.57（含千分位分隔符）
    }
}