如何在 Java 中覆盖数组列表的 toString 方法？
原文:https://www . geesforgeks . org/how-override-to string-method-for-ArrayList-in-Java/
java 中的每个类都是 Object 类的直接或间接的子类。 toString() 存在于对象类中。toString 方法返回对象的字符串表示形式。toString()可以作为类的一部分被重写，以满足用户的定制需求。每当我们试图打印对象引用时，就会在内部调用 toString()方法。如果我们没有在您的类中定义 toString()方法，那么将调用 Object 类 toString() 方法，否则将调用我们实现的/被覆盖的 toString()方法。
对象类 toString()方法的语法:
public String toString()
{
return getClass().getName()+"@"+Integer.toHexString(hashCode());
}
返回:该方法返回一个字符串。
示例:
Java
// Java program to demonstrate
// how to override toString
// method for ArrayList
import java.util.ArrayList;
// define a class
class Employee {
// attributes of an Employee
private String EmployeeName;
private int EmployeeId;
private double EmployeeSalary;
// Create Constructor that accept
// name id and salary as
// an argument
Employee(String name, int id, double salary)
{
this.EmployeeSalary = salary;
this.EmployeeName = name;
this.EmployeeId = id;
}
// Override toString()
// provide your own implementation
public String toString()
{
return " Employee Name = " + this.EmployeeName
+ " Employee Id = " + this.EmployeeId
+ " Employee Salary = "
+ this.EmployeeSalary;
}
}
public class GFG {
public static void main(String[] args)
{
// Create a ArrayList of Employee Class Type
ArrayList<Employee> ArrList
= new ArrayList<Employee>();
ArrList.add(new Employee("Mukul", 1001, 52000.0));
ArrList.add(new Employee("Robin", 1002, 65000.0));
ArrList.add(new Employee("Rahul", 1003, 53000.0));
ArrList.add(new Employee("Suraj", 1004, 45000.0));
ArrList.add(new Employee("Akash", 1005, 38000.0));
// When an object is tried to print
// toString() method is called
for (Employee t : ArrList) {
System.out.println(t);
}
}
}
输出
Employee Name = Mukul Employee Id = 1001 Employee Salary = 52000.0
Employee Name = Robin Employee Id = 1002 Employee Salary = 65000.0
Employee Name = Rahul Employee Id = 1003 Employee Salary = 53000.0
Employee Name = Suraj Employee Id = 1004 Employee Salary = 45000.0
Employee Name = Akash Employee Id = 1005 Employee Salary = 38000.0
说明:当我们尝试打印 Employee 实例时，调用被覆盖的 toString()方法，并打印字符串值。
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