Java之ArrayList练习题

题目1

某班级有若干学生，学生对象存放在一个 List 中，每个学生有姓名（String）、班级（String）、成绩（double）属性，某次考试成绩结束后每个学生都获得了成绩。遍历list集合，把所有学生的属性都打印出来。

import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

/**
 * Created with IntelliJ IDEA
 * Description:
 * User: 23006
 * Date: 2021-11-29
 * Time: 19:23
 * main: psvm
 * 打印: sout
 */

class Student {
    
    
    private String name;
    private String classes;
    private double score;

    public Student(String name, String classes, double score) {
    
    
        this.name = name;
        this.classes = classes;
        this.score = score;
    }

    public String getName() {
    
    
        return name;
    }

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

    public String getClasses() {
    
    
        return classes;
    }

    public void setClasses(String classes) {
    
    
        this.classes = classes;
    }

    public double getScore() {
    
    
        return score;
    }

    public void setScore(double score) {
    
    
        this.score = score;
    }

    @Override
    public String toString() {
    
    
        return "Student{" +
                "name='" + name + '\'' +
                ", classes='" + classes + '\'' +
                ", score=" + score +
                '}';
    }
}

public class TestDemo {
    
    
    public static void main(String[] args) {
    
    
        ArrayList<Student> students = new ArrayList<>();
        students.add(new Student("bit", "102-1", 98.9));
        students.add(new Student("张三", "102-1", 88.8));
        students.add(new Student("李四", "102-1", 90.0));
        System.out.println(students);
    }
}

题目2

删除第一个字符串当中出现的第二个字符串中的字符：
如：

思路：获取第一个字符串str1的每个字符，创建一个ArrayList对象 list，将第二个字符串str2不包含str1中出现的字符add()到 list 中

 String str1 = "welcome to cqupt";
 String str2 = "come";
输出：wl t qupt

public class TestDemo {
    
    
    public static void main(String[] args) {
    
    
        String str1 = "welcome to cqupt";
        String str2 = "come";
        ArrayList<Character> list = new ArrayList<>();
        for (int i = 0; i < str1.length(); i++) {
    
    
            char ch = str1.charAt(i);
            if (!str2.contains(ch + "")) {
    
    
                list.add(ch);
            }
        }
        for (char ch : list) {
    
    
            System.out.print(ch);
        }
    }
}

题目3

有一个List中存放的整形的数据，要求使用Collections.sort对List进行排序。

public static void main(String[] args) {
    
    
        ArrayList<Integer> integers = new ArrayList<>();
        integers.add(11);
        integers.add(2);
        integers.add(13);
        Collections.sort(integers);//排序
        System.out.println(integers);
    }