JAVA-构造方法和文件提取

Student 类

public class Student {

    private String name;
    private int age;
    private double grade;

    public Student(){

    }

    public String getName() {
        return name;
    }

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

public class Main {
    public static void main(String[] args) {
        Student student = new Student();
        student.setName("chy");
        String name = student.getName();
        System.out.println(name);

    }
}

构造器重载

public class Student {

    private String name;
    private int age;
    private double grade;

    public Student(String name,int age,double grade){
        this.age=age;
        this.name=name;
        this.grade=grade;
    }
}

public class Main {
    public static void main(String[] args) {
        Student student = new Student("chy",21,4.0);
        
    }
}

读取文件

public class Main {
    public static void main(String[] args) throws FileNotFoundException {
        Student[] students = null;
        InputStream is  = new FileInputStream("data\\info.txt");
    }
}

Student .java

public class Student {

    private String name;
    private int age;
    private double grade;

    public Student(String name,int age,double grade){
        this.age=age;
        this.name=name;
        this.grade=grade;
    }

    public String msg(){
        return "this STU name is " + name + "age is" + age + "grade is "+ grade;
    }
}

Main.java

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws FileNotFoundException {
        Student[] students = null;
        InputStream is  = new FileInputStream("data\\info.txt");
        Scanner scanner = new Scanner(is,"UTF-8");

//        写循环
        while (scanner.hasNext()){
            String line = scanner.nextLine();
            String[] tokens = line.split(",");

            String name = tokens[0];
            int age = Integer.valueOf(tokens[1]);
            double grade = Double.valueOf(tokens[2]);

            Student student = new Student(name,age,grade);
            System.out.println(student.msg());

        }
    }
}

this STU name is Aliceage is21grade is 3.9
this STU name is bobage is22grade is 3.0
this STU name is chyage is21grade is 4.0

输出

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws IOException {
        Student[] students = null;
        InputStream is  = new FileInputStream("data\\info.txt");
        Scanner scanner = new Scanner(is,"UTF-8");

//        行数
        int Count = Integer.valueOf(scanner.nextLine());
        students = new Student[3];


//        写循环
        for (int i =0; i < Count; i++) {
            String line = scanner.nextLine();
            String[] tokens = line.split(",");

            String name = tokens[0];
            int age = Integer.valueOf(tokens[1]);
            double grade = Double.valueOf(tokens[2]);
            students[i] = new Student(name, age, grade);
        }

        for (Student stu : students){
            System.out.println(stu.msg());
        }

        is.close();

    }