if-statement - 如果条件与 JOptionPane showMessageDialog 一起使用

Question

下面的代码在运行时只生成最后一个学生的名字，分数<30 我希望学生的所有名字都显示在同一个消息对话框中。请帮忙。谢谢，我对编码还很陌生。

import javax.swing.JOptionPane;
class marks
{
    public static void main(String args[])
    {
    String name=" ";
    int marks=0;

    for(int x=0; x<3; x++) 
        {
        name=JOptionPane.showInputDialog(null,"Please enter the name");
        marks=Integer.parseInt(JOptionPane.showInputDialog(null,"Please enter the marks"));
        }

    if (marks<30)
            {
        (JOptionPane.showMessageDialog(null,"the students who got marks below 30 are: "+name));
        }
    }
}

Answer 1

我认为您需要阅读一些基础知识。同样为此目的使用数组而不是一个变量。我更改了您的代码，我认为它可以满足您的要求：

public class marks {

    public static void main(String args[]) {
        int count = 3;
        String[] name = new String[3];
        int[] marks = new int[3];
        for (int x = 0; x < count; x++) {
            name[x] = JOptionPane.showInputDialog(null, "Please enter the name");
            marks[x] = Integer.parseInt(JOptionPane.showInputDialog(null,"Please enter the marks"));
        }
        String names="";
        for(int i = 0;i<count;i++){
            if (marks[i] < 30){
                names+= name[i]+", ";
            }
        }
        if(names.endsWith(", ")){
            names = names.substring(0,names.length()-2);
        }
        if(!names.isEmpty()){
            JOptionPane.showMessageDialog(null,"the students who got marks below 30 are: " + names);
        }
    }
}

Answer 2

import java.util.ArrayList;
import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
class marks
{

    public static void main(String args[])
    {int x=0;
//    String name=" ";
//    int marks=0;
    ArrayList<Integer> marks= new ArrayList<Integer>();
     ArrayList<String> name= new ArrayList<String>();
    ArrayList<String> array = new ArrayList<String>();
    for(x=0; x<3; x++)
        {
        name.add(JOptionPane.showInputDialog(null,"Please enter the name"));
        marks.add(Integer.parseInt(JOptionPane.showInputDialog(null,"Please enter the marks")));

    }

   // if (marks<30)
    for(x=0 ; x<name.size(); x++)
            {

             if(marks.get(x)<30){
           array.add(name.toString());
//         JOptionPane.showMessageDialog(null,"the students who got marks below 30 are: "+name.);
           break;
        }

    }
     JOptionPane.showMessageDialog(null, new JScrollPane(new JList(array.toArray())));
}
}