Java 入门20 ArrayList 小案例实践
2022/6/24 14:20:40
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案例一 删除 成绩中不满住80分的成绩
package com.heima.StringDemo; import java.util.ArrayList; public class ArrayList3 { public static void main(String[] args) { //创建ArrayList 对象 并使用泛型指定整数 ArrayList<Integer> list = new ArrayList(); //添加同学的成绩 list.add(98); list.add(77); list.add(66); list.add(89); list.add(79); list.add(50); list.add(100); //循环ArrayList for (int i = 0; i < list.size(); i++) { System.out.println(list.get(i)); //判断成绩是否低于80 低于80 则删除 if (list.get(i) <=80) { list.remove(i); //从前面往后面删除 删除元素值后,后面的元素值要向前挪 所以i--; i--; } } //打印删除后的学生成绩 System.out.println(list); } }View Code
案例二 影片信息在程序中的存储
Movie 类
package com.heima.StringDemo; public class Movie { private String name; private double scores; private String filmPerson; //创造无参构造器 public Movie() { } //创造有参构造器 public Movie(String name, double scores, String filmPerson) { this.name = name; this.scores = scores; this.filmPerson = filmPerson; } //set get方法创建 public String getName() { return name; } public void setName(String name) { this.name = name; } public double getScores() { return scores; } public void setScores(double scores) { this.scores = scores; } public String getFilmPerson() { return filmPerson; } public void setFilmPerson(String filmPerson) { this.filmPerson = filmPerson; } }View Code
Test 测试类
package com.heima.StringDemo; import java.util.ArrayList; import java.util.Scanner; /* 电影Test类 需求:定义电影类(名称,分值,演员),创建3个电影对象,代表散步影片,存入集合中并遍历 */ public class Test { public static void main(String[] args) { //创造一个ArrayList 集合用来存储movies ArrayList<Movie> list = new ArrayList(); Movie a = new Movie("肖申克的救赎", 9.7, "罗伯特"); Movie b = new Movie("霸王别姬", 9.1, "虞姬"); Movie c = new Movie("阿甘正传", 10.0, "阿甘"); list.add(a); list.add(b); list.add(c); for (int i = 0; i < list.size(); i++) { Movie child=list.get(i); System.out.println(child.getName()+"评分"+child.getScores()+"主演"+child.getFilmPerson()); } } }View Code
案例三 元素搜索
Student类
package com.heima.StringDemo; public class Student { private String name; private int studentNum; private int age; private String studentClass; //创建有参构造器 public Student(String name, int studentNum, int age, String studentClass) { this.name = name; this.studentNum = studentNum; this.age = age; this.studentClass = studentClass; } //创建无参构造器 public Student() { } //get set 创建 public String getName() { return name; } public void setName(String name) { this.name = name; } public double getStudentNum() { return studentNum; } public void setStudentNum(int studentNum) { this.studentNum = studentNum; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getStudentClass() { return studentClass; } public void setStudentClass(String studentClass) { this.studentClass = studentClass; } }View Code
Test1 测试类
package com.heima.StringDemo; import java.util.ArrayList; import java.util.Scanner; public class Test1 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); //创建ArrayList 存储Student产生的对象 ArrayList<Student> studentList = new ArrayList<>(); //创建学生 Student Stu = new Student("叶孤城", 20189812, 18, "二年级一班"); Student Stu1 = new Student("东方不败", 20189813, 18, "二年级一班"); Student Stu2 = new Student("西门吹雪", 20189814, 18, "二年级一班"); Student Stu3 = new Student("梅超风", 20189815, 18, "二年级一班"); //添加进StudentList studentList.add(Stu); studentList.add(Stu1); studentList.add(Stu2); studentList.add(Stu3); //循环展示studentList集合中的元素信息 for (int i = 0; i < studentList.size(); i++) { Student child = studentList.get(i); System.out.println(child.getName() + "\t年纪 \t" + child.getAge() + "学号\t" + child.getStudentNum() + "年级\t" + child.getStudentClass()); } while (true) { System.out.println("请输入学号"); int num = sc.nextInt(); Student s = getSearchMsg(studentList, num); if(s!=null){ System.out.println(s.getName() + "\t年纪 \t" + s.getAge() + "学号\t" + s.getStudentNum() + "年级\t" + s.getStudentClass()); System.out.println("查询完毕"); }else{ System.out.println("查无此人"); } //查询结束 } } public static Student getSearchMsg(ArrayList<Student> a, int num) { for (int i = 0; i < a.size(); i++) { Student child = a.get(i); //相同 则匹配上 if (child.getStudentNum() == num) { return child; } } return null;//查无此学号 } }View Code
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