Question

我正在尝试打印每个主题的平均成绩。

当我尝试这样做时，我无法获得十进制值的输出。

四舍五入到最接近的值。

 package cube;
  import java.io.*;
import java.util.Scanner;
  import java.util.Scanner;  
public class ReportCard
  {
    BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
    double DB[][],nos=0; 
    String S="";
    double total1=0, total2=0, total3=0,  total4=0,   total5=0;
    Scanner s = new Scanner(System.in);
    void Input()throws Exception
    {
      System.out.print("Enter The Number Of Students : ");
      nos=Integer.parseInt(br.readLine());
      DB=new double[(int) (nos+1)][20];
      String arrayOfNames[] = new String[(int) nos];
        for (int i = 0; i < arrayOfNames.length; i++) {
            System.out.print("Enter the name of student:");
                arrayOfNames[i] = s.nextLine();


        System.out.print("\nEnter "+arrayOfNames[i]+"'s English   Score : ");
        DB[i][0]=Integer.parseInt(br.readLine());
        total1=total1+DB[i][0];

        System.out.print("Enter "+arrayOfNames[i]+"'s Science Score : ");
        DB[i][1]=Integer.parseInt(br.readLine());
        total2=total2+DB[i][1];

        System.out.print("Enter "+arrayOfNames[i]+"'s Maths  Score : ");
        DB[i][2]=Integer.parseInt(br.readLine());
        total3=total3+DB[i][2];

        DB[i][3]=(int)(DB[i][0]+DB[i][1]+DB[i][2]);
        total4=total4+DB[i][3];

        DB[i][4]=((int)((DB[i][3])*100)/300);
        total5=total5+DB[i][4];



        }



      System.out.println("\n\n\nStudent Name.  English     Science  \t Maths    Total   Percentage     Pass or Fail \n");
      for(int i=0;i<nos;i++)
      {
          System.out.print(""+arrayOfNames[i]+"\t\t");Padd("English  \t ",DB[i][0]);Padd("Science  \t ",DB[i][1]);
        Padd("Maths  \t\t ",DB[i][2]);Padd("Total \t",DB[i][3]);Padd("Percentage\t",DB[i][4]);

if ((DB[i][0])< 50 | (DB[i][1])< 50 | (DB[i][2]) < 50) {

            System.out.print("\t\tFail");
           }
        else {
            System.out.print("\t\tPass");
        }

        System.out.println(S);

        S="";

      }


    //System.out.println(total);
        int j=0;

        DB[j][0]=(int) (total1/nos);
        DB[j][1]=(int) (total2/nos);
        DB[j][2]=(int) (total3/nos);
        DB[j][3]=(int) (total4/nos);
        DB[j][4]=(int) (total5/nos);

        System.out.println(DB[j][0]);
        System.out.println(DB[j][1]);
        System.out.println(DB[j][2]);
        System.out.println(DB[j][3]);
        System.out.println(DB[j][4]);

      System.out.print("\nAverage  ");
      Padd("English   ",DB[j][0]);Padd("Science   ",DB[j][1]);Padd("Maths   ",DB[j][2]);Padd("Total   ",DB[j][3]);Padd("Percentage   ",DB[j][4]);



    }

    void Padd(String S,double dB2)
    {
      double N=dB2;
    int Pad=0,size=S.length();
      while(dB2!=0)
      {
        dB2/=10;
        Pad++;
      }
      System.out.print("    "+N);
      for(int i=0;i<size-Pad-4;i++)
        System.out.print(" ");
          }


    public static void main(String args[])throws Exception
    {
      ReportCard obj=new ReportCard();
      obj.Input();

    }
  }

当我尝试将j的数据类型更改为double时，出现错误“类型不匹配：无法从double转换为int” 2个快速修复程序 1）将强制转换添加到int 2）将j更改为int

任何人都可以帮我解决这个问题。谢谢。

Answer 1

使用整数计算或强制转换为整数将产生整数输出。

所以DB[j][0]=(int) (total1/nos);将是一个整数值。

DB[j][0] = (total1 / nos);应该得出预期值。

问题不是j变量（它是数组的索引），而是计算。

但是，您可以通过定义一些要使用的常量来使代码更具可读性：

private static final int ENG = 0;
private static final int SCI = 1;
private static final int MAT = 2;
private static final int AVG = 3;

DB[i][ENG] = Integer.parseInt(br.readLine());
...

或者更好地为Student上课。例如：

class Student
{
    final String name;
    int englishScore = 0;
    int scienceScore = 0;
    int mathScore = 0;

    public int getEnglishScore()
    {
        return englishScore;
    }

    public Student setEnglishScore(int englishScore)
    {
        this.englishScore = englishScore;
        return this;
    }

    public int getScienceScore()
    {
        return scienceScore;
    }

    public Student setScienceScore(int scienceScore)
    {
        this.scienceScore = scienceScore;
        return this;
    }

    public int getMathScore()
    {
        return mathScore;
    }

    public Student setMathScore(int mathScore)
    {
        this.mathScore = mathScore;
        return this;
    }

    public String getName()
    {
        return name;
    }

    Student(String name)
    {
        this.name = name;
    }
}

另外，为了进行测试，请始终单独输入（可以更改-也许您想从文件中读取？），数据处理和数据输出。

尝试查找平均值时无法打印十进制值

1 个答案: