20165104 第十周课上测试补做

第十周课上测试补做

课程知识点总结

• 排序
  • 有类的源代码，针对某一成员变量排序，让类实现Comparable接口,调用Collection.sort(List)。
  • 没有类的源代码，或者多种排序，新建一个类，实现Comparator接口 调用Collection.sort(List, Compatator)。
• 泛型类声明:
  class 名称<泛型列表>
• 创建链表
  LinkedList<String> mylist=new LinkedList<String>();
• 向链表增加节点
  list.add(E obj);
• 从链表中删除节点
  list.remove(index)
• 升序排序
  public static sort(List<E>list)
• 折半查找list是否含有和参数key一样的元素
  int binarySearch(List<T>,Tkey,compareTo<T>c)

习题补做

排序

• 代码：

import java.util.*;
public class StudentData {
    public  static void main(String[] args) {
        List<Student> list = new LinkedList<>();
        list.add(new Student(20165102,"赵汉森","m",22,99,88,89));
        list.add(new Student(20165103,"赵中楷","m",21,77,99,76));
        list.add(new Student(20165104,"孟凡斌","m",20,88,77,78));
        list.add(new Student(20165105,"岳怀宇","m",21,99,87,90));
        list.add(new Student(20165106,"陈远","m",20,98,78,93));
        SortByTotal_score sortBytotal_score = new SortByTotal_score();
        Collections.sort(list, sortBytotal_score);
        SortByID sortByID = new SortByID();
        Collections.sort(list, sortByID);
        System.out.println("根据学生学号由低到高排序：");
        for (Student student : list) {
            System.out.println(student);
        }

        Collections.sort(list, sortBytotal_score);
        System.out.println("根据学生成绩由低到高排序：");
        for (Student student : list) {
            System.out.println(student);
        }
    }
}
class Student {

    private int id;//表示学号
    private String name;//表示姓名
    private int age;//表示年龄
    private String sex;//表示性别
    private double computer_score;//表示计算机课程的成绩
    private double english_score;//表示英语课的成绩
    private double maths_score;//表示数学课的成绩
    private double total_score;// 表示总成绩
    private double ave_score; //表示平均成绩

    @Override
    public String toString() {
        return "Student[name:"+name+",age:"+age+",number:"+id+",total_score"+total_score+"]";
    }

    public Student(int id, String name, String sex, int age, double computer_score, double english_score, double maths_score) {
        this.id = id;
        this.name = name;
        this.sex = sex;
        this.age = age;
        this.computer_score = computer_score;
        this.english_score = english_score;
        this.maths_score = maths_score;
    }

    public String getName() {
        return name;
    }
    public int getId() {
        return id;
    }//获得当前对象的学号，

    public double getComputer_score() {
        return computer_score;
    }//获得当前对象的计算机课程成绩,

    public double getMaths_score() {
        return maths_score;
    }//获得当前对象的数学课程成绩,

    public double getEnglish_score() {
        return english_score;
    }//获得当前对象的英语课程成绩,



    public void setName(String name) {
        this.name = name;
    }
    public void setId(int id) {
        this.id = id;
    }// 设置当前对象的id值,

    public void setComputer_score(double computer_score) {
        this.computer_score = computer_score;
    }//设置当前对象的Computer_score值,

    public void setEnglish_score(double english_score) {
        this.english_score = english_score;
    }//设置当前对象的English_score值,

    public void setMaths_score(double maths_score) {
        this.maths_score = maths_score;
    }//设置当前对象的Maths_score值,

    public double getTotalScore() {
        total_score=computer_score + maths_score + english_score;
        return total_score;
    }// 计算Computer_score, Maths_score 和English_score 三门课的总成绩。

    public double getAveScore() {
        return getTotalScore() / 3;
    }// 计算Computer_score, Maths_score 和English_score 三门课的平均成绩。

}

class SortByID implements Comparator<Student> {

    @Override
    public int compare(Student o1, Student o2) {
        return o1.getId() - o2.getId();
    }

}
class SortByTotal_score implements Comparator<Student> {

    @Override
    public int compare(Student o1, Student o2) {
        return (int)( o1.getTotalScore() - o2.getTotalScore());
    }
}

• 实验结果截图
  

单链表

• 代码：

import java.util.Iterator;

public class MyList {
    public static void main(String[] args) {
        //选用合适的构造方法，用你学号前后各两名同学的学号创建四个结点
        Node<Integer> S1 = new Node<Integer>(20165102, null);
        Node<Integer> S2 = new Node<Integer>(20165103, null);
        Node<Integer> S3 = new Node<Integer>(20165105, null);
        Node<Integer> S4 = new Node<Integer>(20165106, null);
        //把上面四个节点连成一个没有头结点的单链表
        S1.next = S2;
        S2.next = S3;
        S3.next = S4;
        //遍历单链表，打印每个结点的
        Node<Integer> s = S1;
        while (s != null) {
            System.out.println(s.data);
            s = s.next;
        }
        System.out.println();
        //把你自己插入到合适的位置（学号升序）
        Node<Integer> M = new Node<Integer>(20165104, null);
        s = S1;
        while (s != null) {
            if (s.data < 20165104 && s.next.data > 20165104) {
                M.next = s.next;
                s.next = M;
                break;
            }
            else {
                s = s.next;
            }
        }
        System.out.println();
        //遍历单链表，打印每个结点的
        s = S1;
        while (s != null) {
            System.out.println(s.data);
            s = s.next;
        }
        System.out.println();
        //从链表中删除自己
        s = S1;
        while (s != null) {
            if (s.next.data == 20165104) {
                s.next = s.next.next;
                break;
            }
            else {
                s = s.next;
            }
        }
        System.out.println();
        //遍历单链表，打印每个结点的
        s = S1;
        while (s != null) {
            System.out.println(s.data);
            s = s.next;
        }
    }
}

• 实验结果截图
  

第十五章课后编程题

（1）使用堆栈结构输出an的若干项，其中an=2an-1+2an-2，a1=3，a2=8

• 代码：

import java.util.*;
    public class T1 {
        public static void main(String[] args) {
            Stack<Integer> stack=new Stack<Integer>();
            stack.push(new Integer(3));
            stack.push(new Integer(8));
            int k=1;
            while (k<=10) {
                for (int i=1;i<=2;i++) {
                    Integer F1=stack.pop();
                    int f1=F1.intValue();
                    Integer F2=stack.pop();
                    int f2=F2.intValue();
                    Integer temp= 2 * f1 + 2 * f2;
                    System.out.println(""+temp.toString());
                    stack.push(temp);
                    stack.push(F2);
                    k++;
                }
            }
        }
    }

• 运行结果截图：
  

(2)将链表中的学生英语成绩单存放到一个树集中，使得按成绩自动排序，并输出排序结果

• 代码：

import java.util.*;
class CollegeStu implements Comparable {
    int english=0;
    String name;
    CollegeStu(int english,String name) {
        this.name=name;
        this.english=english;
    }
    @Override
    public int compareTo(Object b) {
        CollegeStu stu=(CollegeStu)b;
        return (this.english-stu.english);
    }
}
public class T2 {
    public static void main(String[] args) {
        List<CollegeStu> list=new LinkedList<CollegeStu>();
        int score []={ 90, 88, 80};
        String name []={"张三","李四","王五"};
        for (int i=0;i<score.length;i++) {
            list.add(new CollegeStu(score[i],name[i]));
        }
        Iterator<CollegeStu> iter=list.iterator();
        TreeSet<CollegeStu> mytree=new TreeSet<CollegeStu>();
        while (iter.hasNext()) {
            CollegeStu stu=iter.next();
            mytree.add(stu);
        }
        Iterator<CollegeStu> te=mytree.iterator();
        while (te.hasNext()) {
            CollegeStu stu=te.next();
            System.out.println(""+stu.name+" "+stu.english);
        }
    }
}

• 运行结果截图：
  

(3)有10个U盘，有两个重要的属性：价格和容量，编写一个应用程序，使用TreeMap<K,V>类，分别按照价格和容量排序输出10个U盘的详细信息。

• 代码：

import java.util.*;
class UDiscKey implements Comparable {
    double key=0;
    UDiscKey(double d) {
        key=d;
    }
    @Override
    public int compareTo(Object b) {
        UDiscKey disc=(UDiscKey)b;
        if((this.key-disc.key)==0) {
            return -1;
        }
        else {
            return (int) ((this.key - disc.key) * 1000);
        }
    }
}
class UDisc{
    int amount;
    double price;
    UDisc(int m,double e) {
        amount=m;
        price=e;
    }
}
public class T3 {
    public static void main(String args[ ]) {
        TreeMap<UDiscKey,UDisc>  treemap= new TreeMap<UDiscKey,UDisc>();
        int amount[]={8,16,32,64};
        double price[]={40,50,64,128};
        UDisc UDisc[]=new UDisc[4];
        for(int k=0;k<UDisc.length;k++) {
            UDisc[k]=new UDisc(amount[k],price[k]);
        }
        UDiscKey key[]=new UDiscKey[4] ;
        for(int k=0;k<key.length;k++) {
            key[k]=new UDiscKey(UDisc[k].amount);
        }
        for(int k=0;k<UDisc.length;k++) {
            treemap.put(key[k],UDisc[k]);
        }
        int number=treemap.size();
        Collection<UDisc> collection=treemap.values();
        Iterator<UDisc> iter=collection.iterator();
        while(iter.hasNext()) {
            UDisc disc=iter.next();
            System.out.println(""+disc.amount+"G "+disc.price+"元");
        }
        treemap.clear();
        for(int k=0;k<key.length;k++) {
            key[k]=new UDiscKey(UDisc[k].price);
        }
        for(int k=0;k<UDisc.length;k++) {
            treemap.put(key[k],UDisc[k]);
        }
        number=treemap.size();
        collection=treemap.values();
        iter=collection.iterator();
        while(iter.hasNext()) {
            UDisc disc=iter.next();
            System.out.println(""+disc.amount+"G "+disc.price+"元");
        }
    }
}

• 运行结果截图：