Java小数中的四舍五入

时间 2019-12-13

原文原文链接

1.怎么设置显示小数位数dom

    public static void main(String[] args) {
        DecimalFormat decimalFormat = new DecimalFormat("0.00");
        Random random = new Random();
        for (int i = 0; i < 20; i++) {
            double v = random.nextDouble();
            System.out.println("double = "+v+", format = " + decimalFormat.format(v));
        }
　　}

默认四舍五入，源码里面有七八种舍的方法，不知道具体的区别spa

2.进一法设置（后面所有不要，而后前面进一）code

    public static void main(String[] args) {
        DecimalFormat decimalFormat = new DecimalFormat("0.00");
        decimalFormat.setRoundingMode(RoundingMode.UP); // 进一法
        Random random = new Random();
        for (int i = 0; i < 20; i++) {
            double v = random.nextDouble();
            System.out.println("double = "+v+", format = " + decimalFormat.format(v));
        }
    }

3.固然还有不进行四舍五入的例子orm

    public static void main(String[] args) {
        DecimalFormat decimalFormat = new DecimalFormat("0.00");
        decimalFormat.setRoundingMode(RoundingMode.DOWN); // 不进行四舍五入
        Random random = new Random();
        for (int i = 0; i < 20; i++) {
            double v = random.nextDouble();
            System.out.println("double = "+v+", format = " + decimalFormat.format(v));
        }
    }