java - 创建带有使用数组更改文本的单选按钮的面板

Question

我目前对如何使用数组来完成作业感到困惑。我浏览了论坛并使用了谷歌，但运气不佳。我真的很感激有人可以提供的任何建议。非常感谢!:

1. 为我的 2 组单选按钮以及字体大小和字体创建数组

2. 删除所有对单个 JRadioButton 的引用(style1、style2、....size1、size2 等)。相反，必须使用数组值。完成所有代码的修改后，我只需要在一个地方更改程序即可更改大小的所有方面。例如，更改字体数组中的值应该更改字体大小选项和显示该字体大小的标签。

3. JRadioButton 数组的大小应该与 int 和 String 数组的长度直接相关。因此，如果我有六种不同的尺寸可供选择，那么您的数组中应该有六个 JRadioButton。

4. 通过向您的样式数组添加两个额外的字体样式来测试您的代码。

5. 通过向您的大小数组添加两个额外的大小来测试您的代码。

6. 您可能必须修改您的 actionPerformed 方法以匹配第 5 章中检查特定事件的 JRadioButtons 示例中的方法。

因此，在我尚未初始化的两个数组中，我将它们的大小设置为 7，以便我可以添加另外两种大小和两种字体。我对如何在 actionListener 中调用数组的索引感到困惑。什么是使用单选按钮和数组的好教程？

这是我当前的代码:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class StyleArrays extends JPanel implements ActionListener
{
 //declare the labels, panels, variables and radio buttons

 private JLabel saying;
 private JRadioButton style1, style2, style3, style4;
 private JRadioButton size1, size2, size3, size4;
 private JPanel top, right, left;

 JRadioButton[] size = new JRadioButton[7];
 JRadioButton[] font = new JRadioButton[7];
 String[] fonts = {"Arial", "Thonburi", "Rockwell", "Century Gothic"};
 int[] sizes = {18, 22, 26, 30};

 //declare the variables used later in the code the set the font and style
 //private String myFont = "Arial";
 //private int size = 18;

 //Constructor
 //-----------------------------------------------------------------
 public StyleArrays()
 {

  //set the layout of the Layouts panel that will contain all of the other panels
  setLayout (new BorderLayout());
  setBackground (Color.red);

  //create the new panels that will go inside the Layouts panel
  top= new JPanel();
  right= new JPanel();
  left= new JPanel();

  saying = new JLabel ("Say it with style!");
 // saying.setFont (new Font (myFont, Font.PLAIN, size));

  //set the layout and color of the top panel, and add the saying
  add(top, BorderLayout.NORTH);
  top.setBackground (Color.yellow);
  top.add(saying);


  //create size radio buttons
  size1 = new JRadioButton ("18", true);
  size1.setBackground (Color.red);
  size2 = new JRadioButton ("22");
  size2.setBackground (Color.red);
  size3 = new JRadioButton ("26");
  size3.setBackground (Color.red);
  size4 = new JRadioButton ("30");
  size4.setBackground (Color.red);

  //add listeners for each size buttons

  size1.addActionListener (this);
  size2.addActionListener (this);
  size3.addActionListener (this);
  size4.addActionListener (this);

  //add these buttons to this button group
  ButtonGroup group1 = new ButtonGroup();
  group1.add (size1);
  group1.add (size2);
  group1.add (size3);
  group1.add (size4);


  //set the layout and color of the left panel
  add(left, BorderLayout.WEST); //add the left panel to the border layout
  left.setLayout (new BoxLayout (left, BoxLayout.Y_AXIS)); //set the layout of left to box layout
  left.setBackground (Color.red); //set the color to red

  //display the buttons on the panel
  left.add (size1);
  left.add (size2);
  left.add (size3);
  left.add (size4);

  //This section deals with the panel that contains the STYLE  information

  add(right, BorderLayout.EAST); //add the right panel to the border layout
  right.setLayout (new GridLayout (2, 2)); //set the layout of right panel to grid layout
  right.setBackground (Color.red); // set the background color of the panel to red

  //create style radio buttons
  style1 = new JRadioButton ("Arial", true);
  style1.setBackground (Color.red);
  style2 = new JRadioButton ("Thonburi");
  style2.setBackground (Color.red);
  style3 = new JRadioButton ("Rockwell");
  style3.setBackground (Color.red);
  style4 = new JRadioButton ("Century Gothic");
  style4.setBackground (Color.red);


  //add listeners for each style button
  style1.addActionListener (this);
  style2.addActionListener (this);
  style3.addActionListener (this);
  style4.addActionListener (this);

  //add these buttons to this button group  
  ButtonGroup group2 = new ButtonGroup();
  group2.add (style1);
  group2.add (style2);
  group2.add (style3);
  group2.add (style4);

  //display the buttons on the panel
  right.add (style1);
  right.add (style2);
  right.add (style3);
  right.add (style4);


 }

 //*****************************************************************
 //  Represents the listener for both check boxes.
 //*****************************************************************


 //*****************************************************************
 //  Represents the listener for the radio buttons.
 //*****************************************************************
 public void actionPerformed (ActionEvent event)
 {

  Object source = event.getSource(); 
  if (source == size1) //if the event is that the size1 button is selected
   size = 18;    //assign 18 to the  variable

  if (source == size2)  
   size = 22; 

  if (source == size3) 
   size = 26; 

  if (source == size4) 
   size = 30; 

  if (source == style1) 
   myFont = "Arial"; 

  if (source == style2)  
   myFont = "Thonburi"; 

  if (source == style3) 
   myFont = "Rockwell"; 

  if (source == style4) 
   myFont = "Century Gothic"; 

  saying.setFont (new Font (myFont, Font.PLAIN, size)); //display the saying with the current value of 'myFont' and 'style'

 }

 public static void main (String[] args)
 {
  JFrame frame = new JFrame ("Style Arrays");
  frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);

  StyleArrays panel = new StyleArrays();
  frame.getContentPane().add (panel);

  frame.pack();
  frame.setVisible(true);
 }

}

Answer 1

对于初学者来说，任何你能用一个对象做的事情，你都可以用那个对象类型的数组值来做。所以如果你有一个 JRadio 按钮数组，并且 RadioButton.addActionListener(this) 是一个合法的调用，Array[0].addActionListener(this) 是一个合法的调用，就像(这是伪代码，不是 Java)

for each index i of Array
   Array[i].addActionListener(this)

鉴于此，您似乎可以使用大小/字体类型等值数组并遍历它们来创建您的按钮。如果数组中有 10 个尺寸，您可以这样做

for each index i of Sizes
    Array[i] = new JRadioButton(i)

或者类似的东西。我认为迭代值以创建/修改对象是这里正在寻找的。