将集合中的信息写入文件；将文件中的数据读到集合

偏执的太偏执、 2022-03-07 10:12 243阅读 0赞

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# 将集合中的信息写入文件；将文件中的数据读到集合 #

2019年03月15日 19:31:23 [\_Rick][Rick] 阅读数：39

# No1:创建一个学生类 #

package com.rick;
    
    public class Student {
    	private String id;
    	private String name;
    	private String age;
    	private String address;
    	public Student() {
    		super();
    		// TODO Auto-generated constructor stub
    	}
    	public Student(String id, String name, String age, String address) {
    		super();
    		this.id = id;
    		this.name = name;
    		this.age = age;
    		this.address = address;
    	}
    	public String getId() {
    		return id;
    	}
    	public void setId(String id) {
    		this.id = id;
    	}
    	public String getName() {
    		return name;
    	}
    	public void setName(String name) {
    		this.name = name;
    	}
    	public String getAge() {
    		return age;
    	}
    	public void setAge(String age) {
    		this.age = age;
    	}
    	public String getAddress() {
    		return address;
    	}
    	public void setAddress(String address) {
    		this.address = address;
    	}
    	@Override
    	public String toString() {
    		return "Student [id=" + id + ", name=" + name + ", age=" + age + ", address=" + address + "]";
    	}
    	
    
    }

## No2.从控制台写入到文件 ##

package com.rick;
    
    import java.io.BufferedWriter;
    import java.io.FileWriter;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.Scanner;
    
    public class ArrayListToFile {
    
    	public static void main(String[] args) throws IOException {
    		//创建学生集合
    		ArrayList<Student> array = new ArrayList<Student>();
    		Scanner sc = new Scanner(System.in);
    		//循环添加学生
    		System.out.println("添加几个学生？");
    		int num = sc.nextInt();
    		for (int i = 0; i < num; i++) {
    			addStudent(array);
    		}
    		//创建输出缓冲流对象
    		BufferedWriter bw = new BufferedWriter(new FileWriter("student.txt"));
    		//循环输出到文件
    		for (Student student : array) {
    			System.out.println(student.toString());
    			bw.write(student.getId()+","+student.getName()+","+student.getAge()+","+student.getAddress());
    			bw.newLine();
    		}
    		bw.close();
    		
    	}
    
    	public static void addStudent(ArrayList<Student> array) {
    		Scanner sc = new Scanner(System.in);
    		String id;
    		// 判断学号是否存在
    		while (true) {
    			System.out.println("请输入学生学号：");
    			id = sc.nextLine();
    			boolean flag = false;
    			for (int i = 0; i < array.size(); i++) {
    				Student s = array.get(i);
    				if (s.getId().equals(id)) {
    					flag = true;
    					break;
    				}
    			}
    			if (flag == true) {
    				System.out.println("该学生已存在，请重新输入：");
    			} else {
    				break;
    			}
    		}
    		System.out.println("请输入学生姓名：");
    		String name = sc.nextLine();
    		System.out.println("请输入学生年龄：");
    		String age = sc.nextLine();
    		System.out.println("请输入学生住址：");
    		String address = sc.nextLine();
    		Student s = new Student();
    		s.setId(id);
    		s.setName(name);
    		s.setAge(age);
    		s.setAddress(address);
    
    		//添加到集合
    		array.add(s);
    		System.out.println("添加成功!");
    	}
    
    }

# #

## No3.从文件读到控制台 ##

package com.rick;
    
    import java.io.BufferedReader;
    import java.io.FileNotFoundException;
    import java.io.FileReader;
    import java.io.IOException;
    import java.util.ArrayList;
    
    public class FileToArrayList {
    	public static void main(String[] args) throws IOException {
    		//创建一个输入缓冲对象
    		BufferedReader br = new BufferedReader(new FileReader("student.txt"));
    		//创建集合对象
    		ArrayList<Student> array = new ArrayList<Student>();
    		//读取文件
    		String line;
    		while((line = br.readLine()) != null){//br.read.line读一行
    			String[] strs = line.split(",");//分割
    			Student s = new Student();
    			s.setId(strs[0]);
    			s.setName(strs[1]);
    			s.setAge(strs[2]);
    			s.setAddress(strs[3]);
    			array.add(s);		
    		}
    		//释放资源
    		br.close();
    		//打印到控制台
    		for (Student student : array) {
    			System.out.println("学号："+student.getId()+"  姓名："+student.getName()
    			+"  年龄："+student.getAge()+"  地址："+student.getAddress());
    		}
    	}
    }

[Rick]: https://me.csdn.net/weixin_44718300