Question

我有简单的数学例子Add，Substract，Divide和Multiply，并且使用变量作为double，如果我使用小数来添加减法或乘法，则想要答案应该是两位小数。

    private void jButton_addActionPerformed(java.awt.event.ActionEvent  
    evt)    {                                            

    double First = Double.parseDouble(jTextField1.getText());
    // Read the Second number
    double Second = Double.parseDouble(jTextField2.getText());
    // Set the Result
    double Result = First + Second;

    jLabel4.setText(String.valueOf(Result));
     }                                           

    private void jButton_substractActionPerformed
   (java.awt.event.ActionEvent evt)   
   {                                                  

    double First = Double.parseDouble(jTextField1.getText());
   // Read the Second number
   double Second = Double.parseDouble(jTextField2.getText());
   // Set the Result
   double Result = First - Second;


   jLabel4.setText(String.valueOf(Result));
   }                                                 

    private void jButton_MultiplyActionPerformed  
   (java.awt.event.ActionEvent  evt)   
   {                                                 

    double First = Double.parseDouble(jTextField1.getText());
    // Read the Second number
    double Second = Double.parseDouble(jTextField2.getText());
    // Set the Result
    double Result = First * Second;


    jLabel4.setText(String.valueOf(Result));

  }                                                

   private void jButton_divideActionPerformed(java.awt.event.ActionEvent 
    evt)   {                                               

    double First = Double.parseDouble(jTextField1.getText());
    // Read the Second number
    double Second = Double.parseDouble(jTextField2.getText());
    // Set the Result
    double Result = First / Second;


    jLabel4.setText(String.valueOf(Result));
    }

如何将结果舍入为两个小数点，如12.38而不是12.379999

Answer 1

使用setRoundingMode告诉它你想要多少小数点。

Answer 2

您可以通过

执行此操作

double round = Math.round(number * 100.0) / 100.0;

其中number是您的十进制数

要打破它 -

double number = 3.14159;
number = Math.round(number * 100);
number = number/100;

输出为3.14

如何用小数点后两位舍入答案

2 个答案: