Java入门基础之重点练习

重点总结

接口：一组规范，一个标准
//COLLECTION家族：list和set

• //collection 接口存储一组不唯一，无序de对象

List接口存储一组不唯一 有序（插入顺序）的对象
ArrayList:实现了长度可变的数组，在内存中分配连续的空间，遍历元素和随机访问元素的效率比较高
LinkedList：采用链表存储方式。插入、删除元素时效率比较高
Set接口存储一组唯一，无序的对象

• //MAP家族

  Map接口存储一组键值对象，提供key到value的映射

继承

习题1.租车公司的简单设计与实现，通过继承来实现Moto ，Car，Bus类
代码如下：
父类抽象类

package day81;public abstract class Moto {    private int no;    private String brand;    private String color;    private double Mile;    public int getNo() {        return no;    }    public void setNo(int no) {        this.no = no;    }    public String getBrand() {        return brand;    }    public void setBrand(String brand) {        this.brand = brand;    }    public String getColor() {        return color;    }    public void setColor(String color) {        this.color = color;    }    public double getMile() {        return Mile;    }    public void setMile(double mile) {        Mile = mile;    }    public Moto() {        super();    }    public Moto(int no, String brand, String color, double mile) {        super();        this.no = no;        this.brand = brand;        this.color = color;        Mile = mile;    }    public abstract void Cal(int days,String no);}

子类

package day81;public class Car extends Moto{    private String Type;    public String getType() {        return Type;    }    public void setType(String type) {        Type = type;    }    public Car(String type) {        super();        Type = type;    }    public Car() {        super();    }    public final void Cal(int day,String type){        if(type.equals("您需要支付的费用是："+"别克商务舱GL8"))            System.out.println("您需要支付的费用是："+600*day);        else if(type.equals("您需要支付的费用是："+"宝马550i"))            System.out.println("您需要支付的费用是："+500*day);        else if(type.equals("别克林荫大道"))            System.out.println("您需要支付的费用是："+300*day);    }}

package day81;public class Bus extends Moto{    private String Seat;    public String getSeat() {        return Seat;    }    public void setSeat(String seat) {        Seat = seat;    }    public Bus() {        super();    }    public Bus(String seat) {        super();        Seat = seat;    }    public final void Cal(int day,String Seat){        if(Seat.equals("大于16座"))            System.out.println("您需要支付的费用是："+1500*day);        else             System.out.println("您需要支付的费用是："+800*day);    }}

Test主函数：

package day81;import java.util.Scanner;public class Test {    public static void main(String[] args) {        System.out.println("******欢迎来到租车公司******");        Scanner input = new Scanner(System.in);        System.out.println("请输入想租的车型（轿车或者客车）：");        String name= input.next();        if(name.equals("轿车")){            Car aCar = new Car();            System.out.println("请输入向租赁的轿车的车型：");            String type = input.next();            System.out.println("请输入想租赁的天数：");            int day = input.nextInt();            aCar.Cal(day, type);        }        else if(name.equals("客车")){            System.out.println("请输入向租赁的客车的座位：");            String type = input.next();            System.out.println("请输入想租赁的天数：");            int day = input.nextInt();            Bus bus = new Bus();            bus.Cal(day, type);        }    }}

效果图：

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接口

练习2.最经典的打印机问题，打印纸张大小和颜色不同，使用接口来实现
代码如下:
接口paper:

package day92;public interface Paper {    void size();}

接口InkBox：

package day92;public interface InkBox {    void use();}

打印机主函数：

package day92;import java.util.Scanner;public class Printer implements InkBox,Paper{    private String paper;    private String color;    public String getPaper() {        return paper;    }    public void setPaper(String paper) {        this.paper = paper;    }    public String getColor() {        return color;    }    public void setColor(String color) {        this.color = color;    }    public Printer(String paper, String color) {        super();        this.paper = paper;        this.color = color;    }    public void size() {        // TODO Auto-generated method stub        if(paper.equals("A4")){            System.out.println("A4");        }        else            System.out.println("B5");    }    public void use() {        // TODO Auto-generated method stub        if(color.equals("彩色")){            System.out.println("彩色");        }        else            System.out.println("黑白");    }    public static void main(String[] args) {        System.out.println("请输入想要打印的纸张大小：");        Scanner input = new Scanner(System.in);        String paper = input.next();        System.out.println("请输入想要打印的纸张颜色：");        String color = input.next();        Printer aPrinter = new Printer(paper, color);        aPrinter.size();        aPrinter.use();    }}

结果如下：

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有关多态，链表遍历，增删改查的知识

练习三.学生信息管理系统，可以实现增删改，使用链表

代码如下：
学生类代码：

package day10;public class Student {    private String name;    private String num;    private int age;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getNum() {        return num;    }    public void setNum(String num) {        this.num = num;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    public Student(String name, String num, int age) {        super();        this.name = name;        this.num = num;        this.age = age;    }    public Student() {        super();    }}

Test1代码：

package day10;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import java.util.Scanner;public class ArrayList1 {    public static void main(String[] args) {        // TODO Auto-generated method stub        Student []a = new Student[5];        List<Student> students = new ArrayList<Student>();        students.add(new Student("001", "li2", 20));        students.add(new Student("002", "li4", 25));        students.add(new Student("003", "li5", 17));        students.add(new Student("004", "li6", 17));        students.add(new Student("005", "li7", 23));        Iterator<Student> i = students.iterator();         while(i.hasNext())//判断下一个元素之后有值         {             Student aStudent = i.next();             System.out.println(aStudent.getName()+" "+aStudent.getNum()+" "+aStudent.getAge());         }         int q = 0;         Scanner input = new  Scanner(System.in);         System.out.println("请输入需要修改的学号：");         String num = input.next();         for (int j = 0; j < 5; j++) {             String aString = students.get(j).getName();             if(num.equals(aString)){                 System.out.println("请输出要修改的学员的姓名：");                 String name = input.next();                 System.out.println("请输出要修改的学员的年龄：");                 int age = input.nextInt();                 students.set(j, new Student(num,name,age));                 Iterator<Student> i1 = students.iterator();                 while(i1.hasNext())//判断下一个元素之后有值                 {                     Student aStudent = i1.next();                     System.out.println(aStudent.getName()+" "+aStudent.getNum()+" "+aStudent.getAge());                 }             }else {                 q++;                 if(q==5){                    System.out.println("对不起，没有此学员");                    break;                  }            }        }    }}

Tesy2代码：

package day10;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import java.util.Scanner;public class ArrayList2 {    public static void main(String[] args) {        // TODO Auto-generated method stub        Student []a = new Student[5];        List<Student> students = new ArrayList<Student>();        students.add(new Student("001", "li2", 20));        students.add(new Student("002", "li4", 25));        students.add(new Student("003", "li5", 17));        students.add(new Student("004", "li6", 17));        students.add(new Student("005", "li7", 23));        Iterator<Student> i = students.iterator();         while(i.hasNext())//判断下一个元素之后有值         {             Student aStudent = i.next();             System.out.println(aStudent.getName()+" "+aStudent.getNum()+" "+aStudent.getAge());         }         Scanner input = new  Scanner(System.in);         System.out.println("请输入需要删除的学号：");         String num = input.next();         int q=0;         for (int j = 0; j < 5; j++) {             String aString = students.get(j).getName();             if(num.equals(aString)){                 System.out.println("删除成功");                 students.remove(j);                 Iterator<Student> i1 = students.iterator();                 while(i1.hasNext())//判断下一个元素之后有值                 {                     Student aStudent = i1.next();                     System.out.println(aStudent.getName()+" "+aStudent.getNum()+" "+aStudent.getAge());                 }                 break;                 }             else {                 q++;                 if(q==5){                    System.out.println("对不起，没有此学员");                    break;                  }            }    }}}