空指针异常问题

package com.xiaoa.array;

import java.util.Scanner;

class Students {
    private String name;
    private long coure;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public long getCoure() {
        return coure;
    }

    public void setCoure(long coure) {
        this.coure = coure;
    }

    public String toString() {
        return this.name;
    }
}

public class A3 {
    public static void main(String[] args) {
        Students c = new Students();
        System.out.println("请输入学生人数：");
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        System.out.println(num);
        Students arr[] = new Students[num];
        
        //要使用数组,之前,必须赋值,否则当然报空指针
        for (int i = 0; i < arr.length; i++) {
            Students s = new Students();
            arr[i] = s;
        }

        for (int i = 0; i < arr.length; i++) {
            System.out.println("请输入第" + (i + 1) + "名孩子的姓名:");
            String name = scan.next();
            arr[i].setName(name);
            System.out.println("请输入第" + (i + 1) + "名孩子的成绩:");
            long coures = scan.nextLong();
            arr[i].setCoure(coures);
        }
        scan.close();
        for (int i = 0; i < arr.length; i++) {
            for (int j = i + 1; j < arr.length; j++) {
                if (arr[j].getCoure() > arr[i].getCoure()) {
                    c = arr[j];
                    arr[j] = arr[i];
                    arr[i] = c;
                }
            }
        }
        System.out.println("按成绩打印如下");
        for (int i = 0; i < arr.length; i++)
            System.out.println(arr[i].getName() + "的成绩是" + arr[i].getCoure());
    }
}

代码很专业,不过,好像少了姓名的非空校验.
package com.xiaoa.array;

import java.util.Arrays;
import java.

import javax.swing.JOptionPane;
class Students {
    private String name;
    private int score;
    public Students(String name, int score) {
        this.name = name;
        this.score = score;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getScore() {
        return score;
    }
    public void setScore(int score) {
        this.score = score;
    }
   
}

public class A3 {
    private static String getInput(String info){
        
        String result = JOptionPane.showInputDialog(null, info);
        try{
            String str = result.trim();
            if(!("".equals(str)||null==str))
                return str;
            JOptionPane.showMessageDialog(null, "输入不合法,姓名不能为空,请重新输入");
        }catch(Exception e) {
            e.printStackTrace();
        }
        return null;
    }
    private static int getIntVal(String info){
        int num = -1;
        try {
            num = Integer.parseInt(info);
        } catch (NumberFormatException e) {
            JOptionPane.showMessageDialog(null, "输入不合法,不能转换为整形数据,请重新输入");
        }
        return num;
    }
   
    public static void main(String[] args) {
        String numStr = getInput("请输入学生人数:");
        int num = getIntVal(numStr);
        while(num<0){
            numStr = getInput("请输入学生人数:");
            num = getIntVal(numStr);
        }
        JOptionPane.showMessageDialog(null, "学生人数:"+num);
        int score = 0;
        Students arr[]=new Students[num];
        for(int i=0;i<arr.length;i++) {
            String name = getInput("请输入第"+(i+1)+"名孩子的姓名");
            while("".equals(name)||null==name){
                name = getInput("请输入第"+(i+1)+"名孩子的姓名");
            }
            
            String scoreStr = getInput("请输入第"+(i+1)+"名孩子的成绩");
            score = getIntVal(scoreStr);
            while(score<0){
                scoreStr = getInput("请输入第"+(i+1)+"名孩子的成绩");
                score = getIntVal(scoreStr);
            }
            arr[i]=new Students(name, score);
        }
        Arrays.sort(arr, new Comparator<Students>() {
            @Override
            public int compare(Students o1, Students o2) {
                return o1.getScore()-o2.getScore();
            }
        });
        StringBuilder sb = new StringBuilder("按成绩打印如下\n");
        for(int i=0;i<arr.length;i++)
            sb.append(String.format("%s的成绩是%d\n", arr[i].getName(), arr[i].getScore()));
        JOptionPane.showMessageDialog(null, sb.toString());
    }
}

加上比较保险，我觉得。比如windows和linux,ios的换行符都不同的。谁知道识别出来的不输入会是什么？

谢谢。