Java学生成绩排序输出的三种不同方法

2023-10-03 18:38| 来源: 网络整理| 查看: 265

要实现学生成绩的排序，要从两方面来考虑如何设计程序。第一方面是选择存储方式第二方面是选择什么样的排序方式以下是三种不同类型的实现：

使用对象数组存储学生信息，冒泡法实现排序使用List存储学生信息，ArrayList冒泡法实现排序利用Comparator接口和Collections类实现自动排序

成绩排序功能实现结果如下

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方法一：数组排序

采用对象数组的方式来存储学生对象，定义班级类，使用数组来保存班级的学生，代码如下

//使用对象数组存储学生信息，使用冒泡排序算法实现排序 public class test { public static void main(String[] args) { // TODO Auto-generated method stub //创建班级并实例化 studentclass sclass=new studentclass(); //添加学生 sclass.createclass(); System.out.println("原始顺序:"); //排序前的输出 System.out.println(sclass.output()); sclass.sort(); System.out.println("数组冒泡排序的结果:"); //冒泡排序后的输出 System.out.println(sclass.output()); } } class student { private String name; private int age; private double grade; public student(String name,int age,double grade) { this.name=name; this.age=age; this.grade=grade; } //置取方法 public double getGrade() { return grade; } public String getName() { return name; } } class studentclass { private student[] stus; private int size; public studentclass(){ size=0; stus=null; } //创建班级方法 public void createclass() { //定义三个数组存放学生的信息 String names[]= {"张三","王五","李四","赵六","孙七"}; double grades[]= {67,78.5,98,76.5,90}; int ages[]= {17,18,18,19,17}; //把name的长度作为数组长度 size=names.length; //创建班级stus stus=new student[size]; for(int i=0;i student temp; //冒泡排序 for(int i=0;i if(stus[j-1].getGrade()>stus[j].getGrade()) { temp=stus[j-1]; stus[j-1]=stus[j]; stus[j]=temp; } } } } //输出方法 public String output() { //StringBuilder表示可变字符字符串 StringBuilder studentinfo=new StringBuilder(); for(int i=0;i public static void main(String[] args) { // TODO Auto-generated method stub studentclass sclass=new studentclass(); sclass.createclass(); //添加一个学生 sclass.add(new student("杨哥",18,70)); System.out.println("原始顺序:"); System.out.println(sclass.output()); sclass.sort(); System.out.println("数组冒泡排序的结果:"); System.out.println(sclass.output()); } } class studentclass { //用到泛类student，stulist保存班级学生 private List stulist; private int size; public studentclass(){ size=0; stulist=null; } public void createclass() { String names[]= {"张三","王五","李四","赵六","孙七"}; double grades[]= {67,78.5,98,76.5,90}; int ages[]= {17,18,18,19,17}; size=names.length; //实例化类型为ArrayList stulist=new ArrayList(); student temp; for(int i=0;i student temp; //冒泡排序 for(int i=0;i //get获取第几个元素 if(stulist.get(j-1).getGrade()>stulist.get(j).getGrade()) { temp=stulist.get(j-1); //set插入当前位置 stulist.set(j-1,stulist.get(j)); stulist.set(j, temp); } } } } public void add(student s) { stulist.add(s); size=stulist.size(); } public String output() { StringBuilder studentinfo=new StringBuilder(); for(student stu:stulist) { studentinfo.append("姓名:"+stu.getName()+"\t成绩:"+stu.getGrade()+"\r\n"); } return studentinfo.toString(); } } class student { private String name; private int age; private double grade; public student(String name,int age,double grade) { this.name=name; this.age=age; this.grade=grade; } public double getGrade() { return grade; } public String getName() { return name; } }

在createclass方法中，根据班级人数创建班级对象stulist的实例，实例类型为ArrayList,应用ArrayList的方法add()将学生对象添加到班级中。其中sort排序过程使用到了ArrayList的两个方法 public E get(int index) 获取第index个元素 public E set(int index, E element) 将元素element插入到对象的第index的位置上其中for(student stu: stulist)就相当于 for(int i=0;i public static void main(String[] args) { // TODO Auto-generated method stub studentclass sclass=new studentclass(); sclass.createclass(); System.out.println("原始顺序:"); System.out.println(sclass.output()); sclass.sort(); System.out.println("数组冒泡排序的结果:"); System.out.println(sclass.output()); } } //实现Comparator接口 class studentComparator implements Comparator { public int compare(student student1,student student2) { double grade1,grade2; grade1=student1.getGrade(); grade2=student2.getGrade(); if(grade1>grade2) { return 1; }else if(grade1 return 0; } } } class studentclass { private List stulist; private int size; public studentclass(){ size=0; stulist=null; } public void createclass() { String names[]= {"张三","王五","李四","赵六","孙七"}; double grades[]= {67,78.5,98,76.5,90}; int ages[]= {17,18,18,19,17}; size=names.length; stulist=new ArrayList(); student temp; for(int i=0;i //创建一个比较器类对象sc，使用静态方法sort实现排序 studentComparator sc=new studentComparator(); Collections.sort(stulist,sc); } public String output() { StringBuilder studentinfo=new StringBuilder(); for(student stu:stulist) { studentinfo.append("姓名:"+stu.getName()+"\t成绩:"+stu.getGrade()+"\r\n"); } return studentinfo.toString(); } } class student { private String name; private int age; private double grade; public student(String name,int age,double grade) { this.name=name; this.age=age; this.grade=grade; } public double getGrade() { return grade; } public String getName() { return name; } }

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