爲什麼我沒有獲得穩定的產出？

Question

即時通訊試圖自學java，下面的代碼是我的嘗試。我沒有得到預期的輸出。我已經在輸出中發佈了我的編碼。

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStreamReader; 
import java.util.Scanner; 
abstract class q2Student 
{ 
String name; 
int roll_no; 
int sub1,sub2,sub3,sub4,sub5; 
int total; 
float grade; 
float per; 
public abstract void getdata() throws IOException; 
//public abstract void show(); 
public void show() 
{ 
    System.out.println ("Roll No. = "+roll_no); 
    System.out.println ("Name = "+name); 
    System.out.println ("Marks of 1st Subject = "+sub1); 
    System.out.println ("Marks of 2nd Subject = "+sub2); 
    System.out.println ("Marks of 3rd Subject = "+sub3); 
    System.out.println ("Marks of 4th Subject = "+sub4); 
    System.out.println ("Marks of 5th Subject = "+sub5); 
    System.out.println ("Total Marks = "+total); 
    System.out.println ("Percentage = "+per+"%"); 
    System.out.println("Grade="+grade); 
} 


} 
class StudDetails extends q2Student{ 
public void getdata() throws IOException 
{ 
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
    System.out.println ("Enter Name of Student"); 
    name = br.readLine(); 
    System.out.println ("Enter Roll No. of Student"); 
    roll_no = Integer.parseInt(br.readLine()); 
    System.out.println ("Enter marks out of 100 of 1st subject"); 
    sub1 = Integer.parseInt(br.readLine()); 
    while(sub1>100){ 
     System.out.println ("you have entered invalid mark, please check again and enter a mark out of 100"); 
     sub1 = Integer.parseInt(br.readLine()); 
    } 
    System.out.println ("Enter marks out of 100 of 2nd subject"); 
    sub2 = Integer.parseInt(br.readLine()); 
    while(sub2>100){ 
     System.out.println ("you have entered invalid mark, please check again and enter a mark out of 100"); 
    sub2 = Integer.parseInt(br.readLine());} 
    System.out.println ("Enter marks out of 100 of 2nd subject"); 
    sub3 = Integer.parseInt(br.readLine()); 
    while(sub3>100){ 
     System.out.println ("you have entered invalid mark, please check again and enter a mark out of 100"); 
    sub3 = Integer.parseInt(br.readLine());} 
    System.out.println ("Enter marks out of 100 of 2nd subject"); 
    sub4 = Integer.parseInt(br.readLine()); 
    while(sub4>100){ 
     System.out.println ("you have entered invalid mark, please check again and enter a mark out of 100"); 
    sub4 = Integer.parseInt(br.readLine());} 
    System.out.println ("Enter marks out of 100 of 2nd subject"); 
    sub5 = Integer.parseInt(br.readLine()); 
    while(sub5>100){ 
     System.out.println ("you have entered invalid mark, please check again and enter a mark out of 100"); 
    sub5 = Integer.parseInt(br.readLine()); 
    } 

} 
public void calculate(){ 
    total=sub1+sub2+sub3+sub4+sub5; 
    per=(total*100)/500; 
    grade=per/10; 
    } 

    public void result(){ 

    if(grade>=9){ 
     System.out.println("Execellent!!passed with distinction"); 
    } 
    else if((grade>=7.5) &&(grade<=8.9)){ 
     System.out.println("first class!!passed with distinction"); 
     } 
    else if((grade>=6)&&(grade<=7.4)){ 
     System.out.println("passed!! first class"); 
    } 
    else{ 
     System.out.println("sorry!! you are failed"); 
    } 
    } 
} 
public class Student extends StudDetails{ 
static int n; 
public static void main(String args[]) throws IOException 
{ 
    Student s=new Student(); 

    System.out.println ("enter the total no of students"); 
    Scanner in=new Scanner(System.in); 
    n=in.nextInt(); 
    System.out.println ("the total no of students"+n); 
    Student id[]=new Student[n];// array object 
    for(int i=0;i<id.length;i++){ 
     s.getdata(); 
     s.show(); 
     s.calculate(); 
     s.result(); 
    } 

     //in.close(); 
} 
} 

我的輸出如下，我給對象數組作爲輸入和2計算的輸出是不是如我所料

enter the total no of students 
2 
the total no of students2 
Enter Name of Student 
ram 
Enter Roll No. of Student 
1 
Enter marks out of 100 of 1st subject 
89 
Enter marks out of 100 of 2nd subject 
98 
Enter marks out of 100 of 2nd subject 
78 
Enter marks out of 100 of 2nd subject 
76 
Enter marks out of 100 of 2nd subject 
87 
Roll No. = 1 
Name = ram 
Marks of 1st Subject = 89 
Marks of 2nd Subject = 98 
Marks of 3rd Subject = 78 
Marks of 4th Subject = 76  
Marks of 5th Subject = 87 
Total Marks = 0   //total im getting 0 
Percentage = 0.0% 
Grade=0.0   // grade 0 but result states passed with first class 
passed!! first class 
Enter Name of Student 
sur 
Enter Roll No. of Student 
2 
Enter marks out of 100 of 1st subject 
65 
Enter marks out of 100 of 2nd subject 
67 
Enter marks out of 100 of 2nd subject 
89 
Enter marks out of 100 of 2nd subject 
86 
Enter marks out of 100 of 2nd subject 
87 
Roll No. = 2 
Name = sur 
Marks of 1st Subject = 65 
Marks of 2nd Subject = 67 
Marks of 3rd Subject = 89 
Marks of 4th Subject = 86 
Marks of 5th Subject = 87 
Total Marks = 350  // same method called in second index calculating properly 
Percentage = 70.0% 
Grade=7.0 
passed!! first class 

Answer 1

for(int i=0;i<id.length;i++){ 
    s.getdata(); 
    s.calculate(); 
    s.show(); 
    s.result(); 
} 

你需要計算你看之前。我不確定，但我沒有仔細閱讀所有的代碼。您應該會看到How do I ask a good question?和How to create a Minimal, Complete, and Verifiable example.

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