Question

所以我的程序也会完成我想要的所有内容，除了在随机数为temps生成时只显示小数点后的2个位置（12.00）。现在正在做的是（12.1234567897654）。

我是java的初学者，这是我自己完成的第一个程序，所以如果答案显而易见，请不要吝啬D：

我尝试过printf和％。2f，但我无法让它工作

public class ArrayOfTemperatures
{
  public static void main(String[] args)
   {

  double [] temp = new double [7];


  double random = Math.random() * 100 + 1;

  temp[0] = Math.random() * 100 + 1;

     //Calculating average          
     int sum = 0;
     for (int i = 0; i < temp.length; i++) {
        temp[i] =  Math.random() * 100 + 1;
        sum += temp[i];
      }

     //average being stated
     double average = (double) sum / temp.length;
     System.out.println("The average temperature is " + average);

    //Temperatures
    for (int i = 0; i < temp.length; i++) {
     temp[i] =  Math.random() * 100 + 1;
     System.out.print("Temperature " + (i + 1) + " is: " + temp[i]);
        if (temp[i] > average){
           System.out.println(" and is above average.");
        }
        else {
           System.out.println(" and is below average.");
        }


      }          

   }         
}

输出的一个例子是：

The average temperature is 42.714285714285715
Temperature 1 is: 14.71803486458223 and is below average.
Temperature 2 is: 33.10321474550992 and is below average. 
Temperature 3 is: 18.661262675746727 and is below average. 
Temperature 4 is: 82.12893152205741 and is above average. 
Temperature 5 is: 90.97086140892438 and is above average. 
Temperature 6 is: 19.609064446916477 and is below average. 
Temperature 7 is: 75.47742502105827 and is above average.

Answer 1

如果您想将其用于显示目的，请使用java.text.DecimalFormat：

new DecimalFormat("#.##").format(dblVar);

如果您需要它进行计算，那么：

Math.floor(value * 100) / 100

Source：Bozho

的原始答案

Answer 2

您可以使用格式化功能。基本上，它与printf一样。尝试

System.out.println(String.format("Temperature %d is: %.2f", i + 1, temp[i]));

Answer 3

Use this 
System.out.printf("%.2f", temp);

Answer 4

只需使用printf：

 System.out.printf ("The average temperature is %.2f", average);

或

System.out.printf("Temperature %d is: %0.2f ", (i + 1), temp[i]);

Answer 5

可以使用String.format()方法

来解决

System.out.println("The average temperature is " + average);

按以下代码替换此行：

System.out.println("The average temperature is " + String.format("%.02f", average));

和

System.out.print("Temperature " + (i + 1) + " is: " + temp[i]);

按以下代码替换此行：

System.out.println("Temperature " + (i + 1) + " is: " + String.format("%.02f", temp[i]));

Java - 只显示两个小数点？

5 个答案: