Question

我刚刚在eclispe中练习java程序，代码如下：

import java.util.*;
class Problem7
{
    public static void main(String args[]){
int num,sum=0,mod_num,count;//Syntax error on token ";", { expected after           
                             //this token. Ques=Why?
System.out.println("Enter a 5 digit number");
try(Scanner n1 = new Scanner(System.in))
{
    num = n1.nextInt();
}
for(count = 0; count <= 4; count=count+1)
{
        mod_num = num%10;
        num=num/10;
        sum = sum+mod_num;
}
System.out.println("The sum off digits is "+sum);
}
}

=============================================== =========================== 上面的代码运行正常，没有任何错误。但是，如果我想使用另一个类作为＆＃34;类sum_of_digits＆＃34;使用以下代码。它开始在课程中显示错误＆＃34; sum_of_digits＆＃34;我甚至在创建对象之前。以下是代码：

import java.util.*;
class sum_of_digits
{
int num,sum=0,mod_num,count;//Syntax error on token ";", { expected after           
                             //this token. Ques=Why?
for(count = 0; count <= 4; count=count+1)
{
        mod_num = this.num%10;
        this.num=this.num/10;
        sum = sum+mod_num;
}
System.out.println("The sum off digits is "+sum);
}

=============================================== ======================= 但是，如果我在方法中包含for循环并进行必要的安排，那么代码工作正常，它运行没有错误，我得到了所需的结果：下面是带有类＆＃34; sum_of_digits＆＃34;的新代码：< / p>

import java.util.*;
class sum_of_digits
{
int num,sum=0,mod_num,count;//Syntax error on token ";", { expected after   
                            //this token
void loop()
{
    for(count = 0; count <= 4; count=count+1)
    {
        mod_num = this.num%10;
        this.num=this.num/10;
        sum = sum+mod_num;
    }
    System.out.println("The sum off digits is "+sum);
}
}

class Problem7 
{
public static void main(String args[])
{
    sum_of_digits digit = new sum_of_digits();
    System.out.println("Enter a 5 digit number");
    try(Scanner n1 = new Scanner(System.in))
    {
        digit.num = n1.nextInt();
    }
    digit.loop();
}
}

我的问题是为什么我不能直接在课堂上声明for循环＆＃34; sum_of_digits＆＃34;？

Answer 1

你在课堂上有一个for循环。这里不允许这样做。

class sum_of_digits
{
    int num, sum=0, mod_num, count;

    for(count = 0; count <= 4; count=count+1)
    {

    }
}

像这样的可执行语句需要在方法，构造函数或初始化程序块中。

class sum_of_digits
{
    int num, sum=0, mod_num, count;

    void loop() {
        for(count = 0; count <= 4; count=count+1)
        {

        }
    }
}

声明变量和赋值

1 个答案: