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Why are my fields initialized to null or to the default value of zero when I've declared and initialized them in my class' constructor?（4个答案）
1小时前关闭。
我已经在输入模块中获取了输入，并在显示模块中显示了它。理想情况下，存储在输入模块变量中的值应该根据指定的格式在显示模块中显示。但是，尽管输入了输入，在构造函数中初始化的变量的默认值还是显示在输出终端中。下面是我的代码：

import java.util.Scanner;

public class Library {
    int acc_num;
    String title, author;
    Scanner sc = new Scanner(System.in);
    
    Library() {
        title = "";
        author = "";
        acc_num = 0;
    }
    
    void input() {
        System.out.println("Enter the title, the name of the author and the accession number of the book in the same order.");
        String title = sc.nextLine();
        String author = sc.nextLine();
        int acc_num = sc.nextInt();
    }
    
    void display() {
        System.out.println("Accession number\tTitle\tAuthor");
        System.out.println(acc_num + "\t" + title + "\t" + author);
    }
    
    void compute() {
        System.out.println("Enter the number of days late");
        int noOfDaysLate = sc.nextInt();
        int fine = 2 * noOfDaysLate;
        System.out.println("Fine: " + fine);
    }
    
    public static void main(String args[]) {
        Library obj = new Library();
        obj.input();
        obj.compute();
        obj.display();
    }
}

• 我添加了构造函数
• 我试着改变模块的顺序
• 我尝试了www.example.com（）和sc. nextLine（）sc.next() and sc.nextLine()