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：

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：

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;
}

}
}

}
}