Question

我目前难以理解如何使用数组来完成作业。我浏览过论坛，用谷歌运气不好。我真的很感激有人可以提供的任何建议。非常感谢！：

为我的2组单选按钮以及字体大小和字体创建数组
删除对单个JRadioButtons（style1，style2，.... size1，size2等）的所有引用。相反，必须使用数组值。修改完所有代码后，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更改字体大小选项和显示该字体大小的标签。
JRadioButton数组的大小应与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，你的阵列中应该有六个JRadioButtons。
通过在样式数组中添加两种额外的字体样式来测试代码。
通过在尺寸数组中添加两个额外尺寸来测试代码。
您可能需要修改actionPerformed方法，以匹配第5章中检查特定事件的JRadioButtons示例。

所以在我的两个数组中，我还没有初始化，我将它们设为7，允许我添加两个以上的字体和两个以上的字体。我对如何在actionListener中调用数组的索引感到困惑。使用单选按钮和数组的好教程是什么？

这是我目前的代码：

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，你可以用一个对象做任何事情，你可以使用该对象类型的数组值。因此，如果你有一个JRadio按钮数组，并且RadioButton.addActionListener（this）是一个合法的调用，那么Array [0] .addActionListener（this）是一个合法的调用，因为它（这是伪代码，而不是Java）

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

鉴于此，看起来您可以使用大小/字体类型等值的数组，并迭代它们来创建按钮。如果数组中有10个大小，则可以

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

或者那些东西。我认为迭代值以创建/修改对象是这里要查找的内容。

Answer 2

您可以从字体数组中创建它们，如下所示：

public class StylePanel extends JPanel implements ActionListener {
 String[] fontArray = {"Arial", "Serif", "Courier", "Consolas"};
 JLabel   label;

 JRadioButton[] fontButtons = new JRadioButton[fontArray.length];
 ButtonGroup    fontGroup = new ButtonGroup();

 public StylePanel() {
  setLayout(new FlowLayout());
  label = new JLabel("Hello");
  add(label);
  for(int i = 0; i < fontButtons.length; i++) {
   fontButtons[i] = new JRadioButton();
   fontButtons[i].setText(fontArray[i]);
   fontButtons[i].addActionListener(this);
   fontGroup.add(fontButtons[i]);
   add(fontButtons[i]);
  }
 }

 @Override
 public void actionPerformed(ActionEvent e) {
  label.setFont(new Font(
    ((JRadioButton)e.getSource()).getText(), Font.PLAIN, 15));
 } 

 public static void main(String[] args) {
  StylePanel panel = new StylePanel();
  JFrame frame = new JFrame();
  frame.getContentPane().add(panel);
  frame.setSize(400, 300);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setVisible(true);
 }
}

相同的大小数组程序，我只是把它留空以保持简短。

使用单选按钮创建面板，使用数组更改文本

2 个答案: