泛型数组列表ArrayList使用实例（运行时自动调整数组容量）

最新推荐文章于 2021-09-06 11:50:43 发布

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#Eclipse #java #泛型数组列表 #ArrayList

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本文介绍Java泛型概念及ArrayList泛型类的应用，通过创建Employee类存储到ArrayList中，并实现员工信息的增加薪资和展示等功能，最后展示了ArrayList转换为数组的方法。

泛型数组列表ArrayList：

ArrayList是一个采用类型参数的泛型类，<>中指定数组保存的元素的对象类型

实例讲解：

创建一个员工类Employee，用于存放到泛型数组中，也就是<>中放的就是Employee，然后main（）方法中实现存储就可以了。

1.创建Employee类，这里没什么好讲的，你应该能看懂

import java.time.LocalDate;

public class Employee {

    private String name;
    private double salary;
    private LocalDate hireDay;

    public Employee(String mName, double mSalary, int year, int month, int day) {
        this.name = mName;
        this.salary = mSalary;
        this.hireDay = LocalDate.of(year, month, day);
    }

    public String getName() {
        return name;
    }

    public double getSalary() {
        return salary;
    }

    public LocalDate getHireDay() {
        return hireDay;
    }

    public void raiseSalary(double byPercent) {
        double raiseValue = salary * byPercent / 100;
        salary += raiseValue;
    }

}

2.创建ArrayListTest类在main（）方法中实现存贮，展现的功能

import java.util.ArrayList;

public class ArrayListTest {

    public static void main(String[] args) {

        //fill the employeeList with the three Employee objects
        ArrayList<Employee> employeeList = new ArrayList<>();

        employeeList.add(new Employee("Jack", 10000, 2018, 1, 1));
        employeeList.add(new Employee("Rose", 20000, 2018, 1, 1));
        employeeList.add(new Employee("Mike", 30000, 2018, 1, 1));

        //raise employee salary by 10%
        for (Employee e : employeeList) {
            e.raiseSalary(10);
        }
        //print out the information about the three employee objects
        for (Employee ee : employeeList) {
            System.out.println(
                    "name=" + ee.getName() + "  " + "salary=" + ee.getSalary() + "  " + "hireDay=" + ee.getHireDay());
        }
    }
}

现在我们的实例就结束了，这里我添加一个ArrayList转换成数组的简单方法

import java.util.ArrayList;

public class ArrayListTest {

    public static void main(String[] args) {

        .........
        //print out the information about the three employee objects
        for (Employee ee : employeeList) {
            System.out.println(
                    "name=" + ee.getName() + "  " + "salary=" + ee.getSalary() + "  " + "hireDay=" + ee.getHireDay());
        }

        //使用toArray（）方法可以很轻松的实现ArrayList转为数组
        Employee[] array = new Employee[employeeList.size()];
        employeeList.toArray(array);

        System.out.println();

        for (Employee eee : array) 
        {

            System.out.println("name=" + eee.getName() + "  " + "salary=" + eee.getSalary() + "  " + "hireDay="
                    + eee.getHireDay());
        }

    }

}