Java 不使用时以双精度隐藏小数位数

我有一个简单的代码：

int num1 = <user input>;
int num2 = <user input>;
String operation = <user input>;
double result = num1 operation num2;

---

尝试这种方法，并查看结果：

Scanner in = new Scanner(System.in);
DecimalFormat df = new DecimalFormat("##.####");
double num = in.nextDouble();
String result = df.format(num);
System.out.println(result);

输出：

3.67
3.67
BUILD SUCCESSFUL (total time: 5 seconds)

8
8
BUILD SUCCESSFUL (total time: 2 seconds)

5
3
/
1.6667
BUILD SUCCESSFUL (total time: 3 seconds)

更新：

3.67
3.67
BUILD SUCCESSFUL (total time: 5 seconds)

8
8
BUILD SUCCESSFUL (total time: 2 seconds)

5
3
/
1.6667
BUILD SUCCESSFUL (total time: 3 seconds)

您可以尝试此符合您要求的程序：

            Scanner in = new Scanner(System.in);
            DecimalFormat df = new DecimalFormat("##.####");
            double result = 0;
            int num1 = in.nextInt();
            int num2 = in.nextInt();
            String operation = in.next();

            if(operation.equals("/")){
                result = (double)num1 / num2;
            }
            else if(operation.equals("*")){
                result = num1 * num2;
            }
            else if(operation.equals("+")){
                result = num1 + num2;
            }
            else if(operation.equals("-")) {
                result = num1 - num2;
            }
            System.out.println(df.format(result));   

测试用例：

3.67
3.67
BUILD SUCCESSFUL (total time: 5 seconds)

8
8
BUILD SUCCESSFUL (total time: 2 seconds)

5
3
/
1.6667
BUILD SUCCESSFUL (total time: 3 seconds)

---

您可能需要检查。您可以检查

Math.ceil（x.y）=Math.floor（x.y）

，如果它们相等，则表示没有小数部分，因此您可以安全地向下转换到

int

，这里类似的答案是，尾随0的是格式的产物……使用decimalformat

decimalformat df=new decimalformat（“####.#”）；df.format（result）

DecimalFormat帮助！谢谢