Question

我遇到一个小问题，让这个程序正常运行。

/**
 *
 * @author Randy
 */
import java.util.Scanner;//Import scanner

public class RandyGilmanhw2a {
    int year_of_birth;
    int age;

    public RandyGilmanhw2a (){//begin constructor
        year_of_birth = 1900;
        age = 0;
    }//end constructor

    public int getYear(){//get year method
        return year_of_birth;
    }//end method

    public int getAge(int year_of_birth){//get year method
        age = 2014 - year_of_birth;
    return age;
    }//end get year method

    public void setYear (int year){//set year method
        this.year_of_birth = year;
    }//end method

    public static void main(String[] args) {//begin main

        RandyGilmanhw2a user1 = new RandyGilmanhw2a();

        Scanner year = new Scanner(System.in);//create a scanner object
        System.out.println("Please enter the year you were born: ");
        int year_of_birth = year.nextInt();

        while( year_of_birth < 1900 || year_of_birth > 2014 ) {//begin while loop
            System.out.println("Please reenter the year you were born." );
            System.out.println("You must have an integer between 1900 and 2014:" );
            System.out.println("\n");

            System.out.println("Please enter the year you were born: ");
            int year_of_birth = year.nextInt();//ERROR OCCURS HERE SAYS VARIABLE
            //year_of_birth ALREADY DEFINED IN METHOD MAIN
        }//end while 

        user1.getAge(year_of_birth);
        System.out.println("You are " + age + " years old." );//ERROR HERE SAYS NON-STATIC
        // VARIABLE age CANNOT BE REFERENCED FROM A STAIC CONTEXT

    }//end main

}//end class

我评论了显示错误的区域。我正在尝试制作一个程序，显示他们进入那个年龄的人的年龄。但是，如果他们在1900年之前或2014年之后进入一年，我希望它要求用户重新进入他们的出生年份。我似乎无法找到问题。任何帮助将不胜感激。

Answer 1

只需删除int声明即可。这样，您就可以重新定义变量。所以，切换这个：

int year_of_birth = year.nextInt();

到此：

year_of_birth = year.nextInt();

Answer 2

在int移除int year_of_birth = year.nextInt();并将年龄输出更改为：

System.out.println("You are " + user1.getAge(year_of_birth) + " years old." );

Answer 3

从int的第二次初始化中删除year_of_birth，您的问题就会消失。

Answer 4

不要在while循环中将year_of_birth再次定义为int，因为您已在循环中定义。

 while( year_of_birth < 1900 || year_of_birth > 2014 ) {//begin while loop
        ...
        year_of_birth = year.nextInt();//just assign next value
        ...
    }

扫描程序对象在While循环中给出错误

4 个答案: