控制台不打印任何内容

Question

它没有打印任何东西，没有错误。请帮助我解决他的错误。我已经尝试了三种打印方法，但仍然没有一种有效，也没有任何错误。

import java.util.ArrayList;

public class JavaEight {

    public static void main(String args[])
    {
        ArrayList<Employee> Emp = new ArrayList<>();
        Employee e1 = new Employee(101, "Ravi", "Delhi", "2000");
        Employee e2 = new Employee(102, "Vineet", "Mangalore", "5000");
        Employee e3 = new Employee(103, "Punit", "Mumbai", "3000");
        Employee e4 = new Employee(104, "Shruti", "Banglore", "6000");
        Employee e5 = new Employee(105, "Ritu", "Hyderabad", "8000");
        
        for(int i=0; i<Emp.size();i++)
        {   
            Employee e = (Employee)Emp.get(i);
            System.out.println(e);
            
        }
        Emp.forEach(i -> System.out.println(Emp));
        
        for(Employee i : Emp)
        {
            System.out.println(Emp);
        }
        
        
    }
    }

Answer 1

缺少emp.add(e1)；etc

您已经创建了employee对象，但没有将它们添加到列表中。因此，列表是空白的，并且不打印任何内容

Answer 2

在您的ArrayList中添加员工。

     ArrayList<Employee> Emp = new ArrayList<>();
        Employee e1 = new Employee(101, "Ravi", "Delhi", "2000");
        Employee e2 = new Employee(102, "Vineet", "Mangalore", "5000");
        Employee e3 = new Employee(103, "Punit", "Mumbai", "3000");
        Employee e4 = new Employee(104, "Shruti", "Banglore", "6000");
        Employee e5 = new Employee(105, "Ritu", "Hyderabad", "8000");
        Emp.add(e1);
        Emp.add(e2);
        Emp.add(e3);
        Emp.add(e4);
        Emp.add(e5);

希望它能解决你的问题。

Answer 3

这是因为您的ArrayList Emp是空的。您已经创建了Employee对象，但尚未将其添加到Emp。像Emp.add(e1)一样将其添加到Emp中。