编写记录列表的Java应用程序

Question

import java.util.Scanner;
import java.awt.Container;
importjavax.swing.*;
public class AM {
public static void main(String[] args) 
{
String s0 = JOptionPane.showInputDialog( "no. of Students" );
  int array [];
  array = new int[s0];
  Scanner s = new Scanner ( System.in);
  String s1 = JOptionPane.showInputDialog( "Enter the Name of Student" );
  String s2 = JOptionPane.showInputDialog("Enter the Exam Marks" );
  String output = "Name of the Student\tExam Marks\n";
  for ( int counter = 0; counter < array.length; counter++ )
     output += counter + "\t" + array[ counter ] + "\n";
  JTextArea outputArea = new JTextArea();
  outputArea.setText( output);
  JOptionPane.showMessageDialog( null, outputArea,
                 "Analysis of Exam Marks",
     JOptionPane.INFORMATION_MESSAGE );
 }
}

为什么array = new int[] <----不能把s0放进去以及如何使数组成为第一个。学生的？

当我使用array = new int [5];时结果:

no．＿＿Ｍarks

1＿＿＿＿＿0

2＿＿＿＿＿0

3＿＿＿＿＿0

4＿＿＿＿＿0

5＿＿＿＿＿0

如何让这个“0”成为考试分数？

Answer 1

Why the array = new int [ ] <----can not put s0 into here and how to make the array be the no. of the students？？

如果您阅读过文档中的语法，您应该知道原因。您应该在方括号中放置一个整数值来分配数组的大小。那里不允许使用字符串。

array = new int[size];  //where size is int

您可以先将 String 解析为 int，并将其放在括号中:

int numStudents= Integer.parseInt(s0);
array = new int[numStudents];  

HOW to make this "0" be the Exam Marks？？

如果您想提示用户输入所有学生的分数，那么您需要将提示包含在循环中:

for(int x=0; x<numStudents; x++){
    String name = JOptionPane.showInputDialog( "Enter the Name of Student" );
    String str = JOptionPane.showInputDialog("Enter the Exam Marks" );
    int marks = Integer.parseInt(str);
    arrNames[x] = name;
    arrMarks[x] = marks;  
}

<小时/>

所以你的完整程序将如下所示:

public static void main(String[] args){
    int numStudents = Integer.parseInt(JOptionPane.showInputDialog("Enter number of students."));

    String[] names = new String[numStudents];
    int[] marks= new int[numStudents];

    //Populate student data
    for(int x=0; x<numStudents; x++){
        String name = JOptionPane.showInputDialog( "Enter the Name of Student" );
        String str = JOptionPane.showInputDialog("Enter the Exam Marks" );
        int marks = Integer.parseInt(str);
        arrNames[x] = name;
        arrMarks[x] = marks;  
    }

    //Display student data    
    StringBuilder sb = new StringBuilder();
    sb.append("Name of the Student\tExam Marks\n");
    for(int x=0; x<numStudents; x++)
        sb.append(names[x] + "\t" + marks[x] + "\n");

    JTextArea outputArea = new JTextArea();
    outputArea.setText(sb.toString());
    JOptionPane.showMessageDialog( null, outputArea, "Analysis of Exam Marks", JOptionPane.INFORMATION_MESSAGE );    
}