day17作业

1.java.util  2.队列先进先出，栈堆先进后出   3.链表  4.LinkedList  5.TreeSet  6.Comparable  7.Map  8.next()

1.AC 2.A 3.D 4.B 5.D 6.C 7.C 8.C 9.CD

1.× 2.√ 3.× 4.× 5.√ 6.√ 7.√ 8.× 9.√ 10.× 11.× 12.√

2.List是有序的集合，使用此接口能够精确控制每个元素插入的位置，用户能够用索引来访问List中的元素，这类似于java的数组。

Set是一种不包含重复的元素的集合，即任意的两个元素都有equals()方法，Set最多有一个null元素。

Map接口，将键映射到值的对象。一个映射不能包含重复的键；每个键最多只能映射到一个值。

3.区别：Vector是线程安全的，效率低。ArrayList是线程不安全的，效率高。

联系：底层都是数组实现的。

4.Hashtable是JDK1.0版本出现的，是线程安全的，效率低；

HashMap是JDK1.2版本出现的，是线程不安全的，效率高；

Hashtable不可以存储null键和null值；

HashMap可以存储null键和null值（目的是为了让后续代码可以继续执行）

 

package com.zuikc.bean;

public class Book {
    private int id;
    private String name;
    private double price;
    private String press;

    public Book() {
        super();
        // TODO Auto-generated constructor stub
    }

    public Book(int id, String name, double price, String press) {
        super();
        this.id = id;
        this.name = name;
        this.price = price;
        this.press = press;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public String getPress() {
        return press;
    }

    public void setPress(String press) {
        this.press = press;
    }

    @Override
    public String toString() {
        return "Book [id=" + id + ", name=" + name + ", price=" + price + ", press=" + press + "]";
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        result = prime * result + ((press == null) ? 0 : press.hashCode());
        long temp;
        temp = Double.doubleToLongBits(price);
        result = prime * result + (int) (temp ^ (temp >>> 32));
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        Book other = (Book) obj;
        if (id != other.id) {
            return false;
        }
        if (name == null) {
            if (other.name != null) {
                return false;
            }
        } else if (!name.equals(other.name)) {
            return false;
        }
        if (press == null) {
            if (other.press != null) {
                return false;
            }
        } else if (!press.equals(other.press)) {
            return false;
        }
        if (Double.doubleToLongBits(price) != Double.doubleToLongBits(other.price)) {
            return false;
        }
        return true;
    }

}

package com.zuikc.kehoutest;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import com.zuikc.bean.Book;

public class Test6 {

    public static void main(String[] args) {
//        demo1();
        Map<Integer, Book> m = new HashMap<>();
        m.put(100, new Book(100,"b1",20.5,"aaa"));
        m.put(101, new Book(101,"b2",21.5,"bbb"));
        m.put(102, new Book(102,"b3",22.5,"ccc"));
        m.put(103, new Book(103,"b4",23.5,"ddd"));
        
        for(Entry<Integer, Book> entry : m.entrySet()) {
            System.out.println(entry.getKey() + "..." + entry.getValue());
        }
    }

    private static void demo1() {
        List<Book> list = new ArrayList<>();
        list.add(new Book(100,"b1",20.5,"aaa"));
        list.add(new Book(101,"b2",21.5,"bbb"));
        list.add(new Book(102,"b3",22.5,"ccc"));
        list.add(new Book(103,"b4",23.5,"ddd"));
        
        for (Book book : list) {
            System.out.println(book.toString());
        }
    }

}

package com.zuikc.bean;

public class Book {
    private int id;
    private String name;
    private double price;
    private String press;

    public Book() {
        super();
        // TODO Auto-generated constructor stub
    }

    public Book(int id, String name, double price, String press) {
        super();
        this.id = id;
        this.name = name;
        this.price = price;
        this.press = press;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public String getPress() {
        return press;
    }

    public void setPress(String press) {
        this.press = press;
    }

    @Override
    public String toString() {
        return "Book [id=" + id + ", name=" + name + ", price=" + price + ", press=" + press + "]";
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + id;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        result = prime * result + ((press == null) ? 0 : press.hashCode());
        long temp;
        temp = Double.doubleToLongBits(price);
        result = prime * result + (int) (temp ^ (temp >>> 32));
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        Book other = (Book) obj;
        if (id != other.id) {
            return false;
        }
        if (name == null) {
            if (other.name != null) {
                return false;
            }
        } else if (!name.equals(other.name)) {
            return false;
        }
        if (press == null) {
            if (other.press != null) {
                return false;
            }
        } else if (!press.equals(other.press)) {
            return false;
        }
        if (Double.doubleToLongBits(price) != Double.doubleToLongBits(other.price)) {
            return false;
        }
        return true;
    }

}

package com.zuikc.kehoutest;

import java.util.HashMap;
import java.util.HashSet;
import java.util.TreeSet;

import com.zuikc.bean.Book;

public class Test7 {

    public static void main(String[] args) {
//        demo1();
        TreeSet<Book> ts = new TreeSet<>();
        ts.add(new Book(100,"b1",20.5,"aaa"));
        ts.add(new Book(100,"b1",20.5,"aaa"));
        ts.add(new Book(101,"b2",21.5,"bbb"));
        ts.add(new Book(101,"b2",21.5,"bbb"));
        ts.add(new Book(102,"b3",22.5,"ccc"));
        ts.add(new Book(103,"b4",23.5,"ddd"));
        
        for(Book book : ts) {
            System.out.println(book);
        }
    }

    private static void demo1() {
        HashSet<Book> hs = new HashSet<>();
        hs.add(new Book(100,"b1",20.5,"aaa"));
        hs.add(new Book(101,"b2",21.5,"bbb"));
        hs.add(new Book(102,"b3",22.5,"ccc"));
        hs.add(new Book(103,"b4",23.5,"ddd"));
        
        for(Book book : hs) {
            System.out.println(book);
        }
    }

}

package com.zuikc.bean;

public class StudentEntry {
    private int key;
    private Student2 s;
    public StudentEntry() {
        super();
        // TODO Auto-generated constructor stub
    }
    public StudentEntry(int key, Student2 s) {
        super();
        this.key = key;
        this.s = s;
    }
    public int getKey() {
        return key;
    }
    public void setKey(int key) {
        this.key = key;
    }
    public Student2 getS() {
        return s;
    }
    public void setS(Student2 s) {
        this.s = s;
    }
    
}

package com.zuikc.kehoutest;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import com.zuikc.bean.Student2;
import com.zuikc.bean.StudentEntry;

public class Test8 {

    public static void main(String[] args) {
//        listToMap();
        Map<Integer, Student2> m = new HashMap<>();
        m.put(100, new Student2(100, "张三", 23, "男"));
        m.put(101, new Student2(101, "李四", 24, "男"));
        m.put(102, new Student2(100, "王五", 25, "男"));
        m.put(103, new Student2(100, "赵六", 26, "男"));
        
        List<StudentEntry> list = new ArrayList<>();
        for(Entry<Integer, Student2> entry : m.entrySet()) {
            StudentEntry se = new StudentEntry();
            se.setKey(entry.getKey());
            se.setS(entry.getValue());
            list.add(se);
        }
        for(StudentEntry se : list) {
            System.out.println(se.getKey() + "..." + se.getS());
        }
    }

    private static void listToMap() {
        List<Student2> list = new ArrayList<>();
        list.add(new Student2(100, "张三", 23, "男"));
        list.add(new Student2(101, "李四", 24, "男"));
        list.add(new Student2(100, "王五", 25, "男"));
        list.add(new Student2(100, "赵六", 26, "男"));
        for (Student2 s : list) {
            System.out.println(s);
        }
        Map<Integer, Student2> m = new HashMap<>();
        Iterator<Student2> it = list.iterator();
        while (it.hasNext()) {
            Student2 s1 = it.next();
            m.put(s1.getId(), s1);
        }

        Set<Entry<Integer, Student2>> entrySet = m.entrySet();
        for (Entry<Integer, Student2> entry : entrySet) {
            System.out.println(entry.getKey() + "..." + entry.getValue());
        }
    }

}

package com.zuikc.kehoutest;

import java.util.HashMap;
import java.util.Map;

public class Test9 {

    public static void main(String[] args) {
        String str = "aa@sohu.com,bb@163.com,cc@sina.com";
        String strs[] = str.split(",");
        Map<String, String> emailMap = new HashMap<String, String>();
        for (String email : strs) {
            String temp[] = email.split("@");
            emailMap.put(temp[0], temp[1]);
        }
        System.out.println(emailMap.toString());
    }

}

package com.zuikc.bean;

public class Student3 implements Comparable<Student3>{
    private int id;
    private String name;
    private int age;
    public Student3() {
        super();
        // TODO Auto-generated constructor stub
    }
    public Student3(int id, String name, int age) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    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 String toString() {
        return "Student3 [id=" + id + ", name=" + name + ", age=" + age + "]";
    }
    @Override
    public int compareTo(Student3 s) {
        return this.age - s.age;
    }
    
}
package com.zuikc.kehoutest;

import java.util.Scanner;
import java.util.Set;

import javax.swing.text.html.HTMLDocument.Iterator;

import com.zuikc.bean.Student3;

public class Test10 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Set<Student3> stuSet = saveStudentInfo();
        Iterator<Student3> it = stuSet.iterator();
        while (it.hasNext()) {
            String info = it.next().toString();
            System.out.println(info);
        }
    }

    private static void saveStudentInfo() {
        while (true) {
            System.out.println("请输入学生信息(编号#姓名#年龄)");
            String line = sc.nextLine();
            if ("exit".equals(line)) {
                break;
            }
            String[] info = line.split("#");
            Student3 stu = new Student3(Integer.parseInt(info[0]), info[1], Integer.parseInt(info[2]));
            stuSet.add(stu);
        }
        return stuSet;
    }

}