java - 构造函数中传递的参数 - Java

Question

我有一个Person类来描述一个人的一些特征:

public class Person {

    private String name;
    private String surname;
    private String birthPlace;
    private int age;

    public Person(String name, String surname, String birthPlace, int age) {
        super();
        this.name = name;
        this.surname = surname;
        this.birthPlace = birthPlace;
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public String getSurname() {
        return surname;
    }
    public String getBirthPlace() {
        return birthPlace;
    }
    public int getAge() {
        return age;
    }
}

在 PersonDemo我创建了 4 个人，并将他们添加到 ArrayList<Person> 中。 。然后我通过ArrayList<Person>到 Frame类(扩展 JFrame ):

import java.util.ArrayList;

public class PersonDemo {

    public static void main(String[] args) {

        Person p1 = new Person("Cristiano","Ronaldo","Santo Antonio", 31);
        Person p2 = new Person("Zlatan","Ibrahimovic","Malmo", 34);
        Person p3 = new Person("Alessandro","Del Piero", "Conegliano", 41);
        Person p4 = new Person("Zinedine","Zidane","Marseille",43);

        //ArrayList<Person>
        ArrayList<Person> people = new ArrayList<>();
        people.add(p1);
        people.add(p2);
        people.add(p3);
        people.add(p4);

        //Create and make visible a new Frame() f passing 
        //as parameter the previous ArrayList<Person>
        Frame f = new Frame(people);
        f.setVisible(true);
    }
}

我用JSplitPane分割了我的框架:

import java.util.ArrayList;

import javax.swing.JFrame;

public class Frame extends JFrame{

    private static final long serialVersionUID = 1L;
    private static final int X_AXIS = 175;
    private static final int Y_AXIS = 25;
    private static final int WIDTH= 930;
    private static final int HEIGHT = 600;

    private SplitPane splitPane;

    public Frame(ArrayList<Person> p) {

        this.setTitle("My Frame");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setBounds(X_AXIS,Y_AXIS,WIDTH,HEIGHT);

        //pass to the splitPane the ArrayList<Person> p
        splitPane = new SplitPane(p);
        this.getContentPane().add(splitPane);   

    }
}

在JSplitPane的左侧我创建了一个新的 JPanel ;在此JPanel我必须处理 ArrayList<Person> :

import java.util.ArrayList;
import javax.swing.JPanel;
import javax.swing.JSplitPane;

public class SplitPane extends JSplitPane{

    private static final long serialVersionUID = 1L;
    private static final int SPLIT_WEIGHT  = 250;
    private JPanel leftPanel;

    public SplitPane(ArrayList<Person> p) {

        //pass to the JPanel leftPanel the ArrayList<Person> p
        leftPanel = new LeftPanel(p);
        this.setOrientation(JSplitPane.HORIZONTAL_SPLIT);
        this.setDividerLocation(SPLIT_WEIGHT);
        this.setLeftComponent(leftPanel);
    }
}

这是我的LeftPanel扩展类JPanel :

import java.util.ArrayList;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class LeftPanel extends JPanel{

    private static final long serialVersionUID = 1L;

    public LeftPanel(ArrayList<Person> p) { 

        JLabel label = new JLabel("This is the left side of \"My Frame\"");
        this.add(label);

        //some code to work with ArrayList<Person> p in this JPanel 
    }
}

不知道是否可以通过ArrayList<Person>在构造函数( JFrame -> JSplitPane -> JPanel )中是一个很好的方法，或者有更好的解决方案(也许是继承)。

Answer 1

实现 UI 程序的常见策略是使用 Model-View-Controller方法。在您的程序中，Swing 类将是 View ，而 Person和ArrayList<Person>将是模型。

View 需要访问模型中的数据，以便向最终用户显示相关部分。授予 View 访问模型相关部分的常用方法有以下三种:

• 在构造函数中传递模型部件 - 这是您采用的方法，
• 使模型成为单例 - 这种方法允许所有 View 访问模型的所有部分，
• 使用控制容器反转 - 这是一种高级方法，可让您以声明性方式配置访问权限。

对于您开发的小程序来说，第三种方法可能太先进了，但是单例可能比显式传递列表更好:

class Model {
    private static List<Person> people;
    public static List<Person> getPeople() {
        return people;
    }
    public static void setPeople(List<Person> people) {
        this.people = people;
    }
}

现在你的main会这样做:

Person p1 = new Person("Cristiano","Ronaldo","Santo Antonio", 31);
Person p2 = new Person("Zlatan","Ibrahimovic","Malmo", 34);
Person p3 = new Person("Alessandro","Del Piero", "Conegliano", 41);
Person p4 = new Person("Zinedine","Zidane","Marseille",43);

//ArrayList<Person>
ArrayList<Person> people = new ArrayList<>();
people.add(p1);
people.add(p2);
people.add(p3);
people.add(p4);
Model.setPeople(people);

你的 Swing 类(class)将不再传播ArrayList<Person> 。相反，他们会这样做Model.getPeople()每次他们需要访问 List<Person> .