Java IO流--练习

1）将若干个Student对象,若干个Teacher对象,写出到d:/0404/a.txt中

2）将该文件中所有Student对象反序列化回来装入List, 所有的Teacher对象反序列化回来转入另外一个List

运用知识点：对象流，文件流

代码：

逻辑—–>建立一个Person类，并实现Serializable。再让Student和Teacher类继承Person。（当然这里没必要，可以直接建立Student和Teacher类）

Person类

package Homework;

import java.io.Serializable;

public class Person implements Serializable {
    private static final long serialVersionUID = 1L;
    private String name;
    private String sex;
    private int age;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "Person [name=" + name + ", sex=" + sex + ", age=" + age + "]";
    }
    public Person(String name, String sex, int age) {
        super();
        this.name = name;
        this.sex = sex;
        this.age = age;
    }
    public Person() {
        super();
    }

}

Student类

package Homework;

public class Student extends Person {
    public Student(String name,String sex,int age){
        super(name, sex, age);
    }
    public Student(){}
    @Override
    public String toString() {
        return "Student [getName()=" + getName() + ", getSex()=" + getSex() + ", getAge()=" + getAge() + "]";
    }
}

Teacher类

package Homework;

public class Teacher extends Person {
    public Teacher(String name,String sex,int age){
        super(name, sex, age);
    }
    public Teacher(){}
    @Override
    public String toString() {
        return "Teacher [getName()=" + getName() + ", getSex()=" + getSex() + ", getAge()=" + getAge() + "]";
    }
}

测试类

package Homework;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;

public class Test1and2 {

    public static void main(String[] args) {
        //在本工程下创建一个文件夹
        File file=new File("Instance");
        file.mkdirs();
        //在本工程下创建的文件夹下创建一个a.txt文件，用来写入对象
        File file2=new File(file,"a.txt");

        //使用对象流写入对象
        ObjectOutputStream oos=null;
        ObjectInputStream ois=null;
        try {
            file2.createNewFile();

            //将若干个Student对象,若干个Teacher对象,写入文件中
            oos=new ObjectOutputStream(new FileOutputStream(file2));
            oos.writeObject(new Student("李四","男",20));
            oos.writeObject(new Student("李四2","男",45));
            oos.writeObject(new Student("李四3","男",38));
            oos.writeObject(new Teacher("张三","男",13));
            oos.writeObject(new Teacher("张三","男",50));
            oos.writeObject(new Teacher("张三","男",34));
            oos.flush();

            //将该文件中所有Student对象反序列化回来装入List
            ois=new ObjectInputStream(new FileInputStream(file2));
            ArrayList<Student> list=new ArrayList<>();
            ArrayList<Teacher> list2=new ArrayList<>();

            //将文件中写入的对象读取出来，并转为对象，存入对应的集合中
            for(int i=0;i<6;i++){
                if(i<=2){
                    Student student=(Student)ois.readObject();
                    list.add(student);
                }else {
                    Teacher teacher=(Teacher)ois.readObject();
                    list2.add(teacher);
                }
            }

            //遍历打印出集合中的对象
            for (Student student : list) {
                System.out.println(student);
            }
            for (Teacher teacher : list2) {
                System.out.println(teacher);
            }

        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            if(ois!=null){
                try {
                    ois.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            if(oos!=null){
                try {
                    oos.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
    }
}

遍历结果：

3）要求从控制台输入两个整数，之后完成两个整数的加法操作

如果输入整数，求和。
如果输入的不是整数：重新输入，比如ddd

注意：要求使用标准流，不能使用Scanner类

代码：

package com.qf.demo2;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Test {

    public static void main(String[] args) {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
         int sum = 0;
        while(true){
            try {
                System.out.println("请输入第一个数：");
                String a = reader.readLine();

                System.out.println("请输入第二个数：");
                String b = reader.readLine();

                //对输入的内容进行正则匹配，判断是否是数字
                boolean flag = a.matches("[0-9]+");
                boolean flag2 = b.matches("\\d+");

                // 如果两次输入的都是数字，那么将两次输入的数据转为整数，并求和，以及退出循环
                if( flag && flag2){
                    sum = Integer.parseInt(a)+Integer.parseInt(b);
                    break;
                }else{
                    // 如果两次输入有一个不是数字，则重新输入，进入循环
                    System.out.println("请重新输入,必须只能包含数字");
                }

            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        System.out.println("输入的两个整数和是："+sum);
    }
}

运行结果：