Java:指定小数点后面的数字

Question

我有一个用于计算数据范围的GUI Java代码,例如,如果输入了两个值2.444,3.555结果将是一个long double 1.11100000...等.如何指定它应显示的小数点后面的位数？(例如:%.2f)

这是我的代码:

public class Range
{
    public static void main(String args[])
    {
        int num=0; //number of data
        double d; //the data
        double smallest = Integer.MAX_VALUE;
        double largest = Integer.MIN_VALUE;
        double range = 0;

        String Num =
        JOptionPane.showInputDialog("Enter the number of data ");
        num=Integer.parseInt(Num);

        for(int i=0; i<num; i++)    
        {
            String D =
            JOptionPane.showInputDialog("Enter the data ");
            d=Double.parseDouble(D);

            if(d < smallest)
                smallest = d;
            if(d > largest)
                largest = d; 
        }

        range = largest - smallest ; //calculating the range of the input

        JOptionPane.showMessageDialog(null,"Range = "+smallest+"-"+largest+" = "+range,"Range",JOptionPane.PLAIN_MESSAGE);
    }
}

Answer 1

您可以使用String.format来定义您喜欢的输出,例如

String.format("Range = %.4f", range)

显示4位小数.