练习题03List

1. 向list集合添加姓名{张三李四，王五二丫,钱六，孙七}，将二丫替换为王小丫。
2. AmayList集合中有如下内容: {33，11，77，55}, 使用Collections sort()对AnmayList 集合中的数据进行排序，并打印出排序后的结果。
3. 成绩排序
   需求:用TreeSet存储多个学生信息(姓名， 语文成绩，数学成绩)，并遍历该集合
   要求:按照总分从高到低出现。
4. 需求:创建一个存储学生对象的集合,存储多个学生对象，使用程序实现在控制台遍历该集合
   要求:学生对象的成员变量值相同，我们就认为是同一个对象

1、
package com.xxx;
 
import java.util.ArrayList;
import java.util.List;
 
public class Test1 {
    public static void main(String[] args) {
        List list = new ArrayList<>();
 
        list.add("张三");
        list.add("李四");
        list.add("王五");
        list.add("二丫");
        list.add("钱六");
        list.add("孙七");
 
        int index = list.indexOf("二丫");
        list.set(index, "王二丫");
        System.out.println(list);
    }
}

2、
package com.xxx;
 
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
 
public class Test02 {
    public static void main(String[] args) {
        List list = new ArrayList();
        list.add(33);
        list.add(11);
        list.add(77);
        list.add(55);
 
        Collections.sort(list);
 
        System.out.println(list);
    }
}

3、
package com.xxx;
 
public class Students {
    private String name;
    private double chineseScore;
    private double mathScore;
 
    public Students() {
    }
 
    public Students(String name, double chineseScore, double mathScore) {
        this.name = name;
        this.chineseScore = chineseScore;
        this.mathScore = mathScore;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public double getChineseScore() {
        return chineseScore;
    }
 
    public void setChineseScore(double chineseScore) {
        this.chineseScore = chineseScore;
    }
 
    public double getMathScore() {
        return mathScore;
    }
 
    public void setMathScore(double mathScore) {
        this.mathScore = mathScore;
    }
 
    @Override
    public String toString() {
        return "Students{" +
                "name='" + name + '\'' +
                ", chineseScore=" + chineseScore +
                ", mathScore=" + mathScore +
                '}';
    }
}
package com.xxx;
 
import java.util.Comparator;
import java.util.TreeSet;
 
public class Test03 {
    public static void main(String[] args) {
 
        TreeSet treeSet = new TreeSet(new Comparator() {
            @Override
            public int compare(Object o1, Object o2) {
                Students s1 = (Students) o1;
                Students s2 = (Students) o2;
                return (int) ((s2.getChineseScore() + s2.getMathScore()) - (s1.getChineseScore()+s1.getMathScore()));
            }
        });
 
        treeSet.add(new Students("路飞", 10, 20));
        treeSet.add(new Students("索隆", 80, 70));
        treeSet.add(new Students("山治", 90, 80));
        treeSet.add(new Students("甚平", 70, 90));
        treeSet.add(new Students("罗宾", 100, 100));
 
        System.out.println(treeSet);
    }
}

4、
package com.xxx;
 
import java.util.Objects;
 
public class Student {
    private String name;
    private int age;
 
    public Student() {
    }
 
    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public int getAge() {
        return age;
    }
 
    public void setAge(int age) {
        this.age = age;
    }
 
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Student student = (Student) o;
        return age == student.age &&
                Objects.equals(name, student.name);
    }
 
    @Override
    public int hashCode() {
        return Objects.hash(name, age);
    }
 
    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}
package com.xxx;
 
import java.util.HashSet;
import java.util.Set;
 
public class Test4 {
    public static void main(String[] args) {
        Set set = new HashSet<Student>();
 
        Student stu1 = new Student("伏黑", 18);
        Student stu2 = new Student("虎杖", 17);
        Student stu3 = new Student("钉崎", 19);
        Student stu4 = new Student("钉崎", 19);
 
        set.add(stu1);
        set.add(stu2);
        set.add(stu3);
        set.add(stu4);
 
        for (Object o : set) {
            System.out.println(o);
        }
    }
}