计算java创建的对象数 [英] count the number of objects created by java

问题描述

我试图计算创建的对象数，但它始终返回1.

I'm trying to count the number of objects created but it always returns 1.

public class Drivertwo {

    public static void main(String[] args) {
        Employee newEmp = new Employee();
        Employee newEmp2 = new Employee();
        Calculate newcal = new Calculate();
        Clerk newclerk = new Clerk();

        float x;
        int y;

        newEmp.setEmp_no(2300);
        newEmp.setEmp_name("W.Shane");
        newEmp.setSalary(30000);
        newEmp.counter();

        newEmp2.setEmp_no(1300);
        newEmp2.setEmp_name("W.Shane");
        newEmp2.setSalary(50000);
        newEmp2.counter();

        newclerk.setEmp_name("Crishane");
        newclerk.setEmp_no(1301);
        newclerk.setGrade(2);
        newclerk.setSalary(45000);
        newclerk.counter();

        System.out.println("Salary is:" + newcal.cal_salary(newclerk.getSalary(), newclerk.getEmp_no()));
        System.out.println("Name is:" + newclerk.getEmp_name());
        System.out.println("Employee number is:" + newclerk.getEmp_no());
        System.out.println("Employee Grade is:" + newclerk.getGrade());
        System.out.println("No of objects:" + newEmp.numb);

这是我班的主要方法

public class Employee {
    private int salary;
    private int emp_no;
    private String emp_name;
    public int numb=0;

    public int getSalary() {
        return salary;
    }

    public int getEmp_no() {
        return emp_no;
    }

    public String getEmp_name() {
        return emp_name;
    }

    public void setSalary(int newSalary) {
        salary = newSalary;
    }

    public void setEmp_no(int newEmp_no) {
        emp_no = newEmp_no;
    }

    public void setEmp_name(String newEmp_name) {
        emp_name = newEmp_name;
    }


    }

    public int counter() {
        numb++;
        return numb;

这是我的员工班级

我尝试在员工类中作为启动器运行计数器，但它始终返回1.我知道我可以在主类中创建一个计数器，每次创建新对象时都可以获取该计数器，但是我想自动增加制作对象时以1的速度麻木.

I tried to run counter in my employee class as a starter but it always returns 1. I know I can make a counter in main class and everytime I make a new object I can get the counter but I want to automatically increase the numb by 1 when an object is made.

推荐答案

您需要将 numb 设为静态，以便该类的每个实例只有一个副本.实际上，每个 Employee 对象都有其自己的 numb 副本.

You need to make numb static so that there will only be one copy for every instance of the class. As it is, every single Employee object has its own copy of numb.

为什么不将其放在构造函数中呢?

Also instead of creating a method to up the counter why not just put it in the constructor:

public Employee() {
   numb++;
}

这篇关于计算java创建的对象数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！