Question

我使用此代码创建了一个带有3x3网格按钮的框架......

    JFrame frame = new JFrame("my 3x3");
    JPanel panel = new JPanel();
    Container pane = frame.getContentPane();
    panel.setLayout(new GridLayout(3,3));
    panel.add(upperLeft);
    panel.add(upperCenter);
    panel.add(upperRight);
    panel.add(midLeft);
    panel.add(midCenter);
    panel.add(midRight);
    panel.add(bottomLeft);
    panel.add(bottomCenter);
    panel.add(bottomRight);
    pane.add(panel);

...每个上下左右元素都是JButton对象。

在执行的后期，我需要一个这些按钮的列表来迭代重置它们，但我在那一点上只有框架。我知道埋在框架对象的某个地方是一个组件列表，也许层深，但在哪里？是否有直接的方法来检索框架的按钮？

Answer 1

每次挥杆Container都有getComponents()。因此，从JFrame（或其getContentPane()）开始，您可以递归下去并获取所有组件。

但是，当您将按钮添加到面板时，您也可以按住List<JButton>并填写它。

Answer 2

由于您的按钮网格是3x3，并且因为您事先知道（在程序运行之前），为什么不创建一个2维3x3按钮数组。然后按钮索引将自然地反映他们的位置。

编辑：例如

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

@SuppressWarnings("serial")
public class ButtonGridGuiPanel extends JPanel {
   // The number of rows and columns
   private static final int MAX_ROWS = 3;
   private static final int MAX_COLS = MAX_ROWS;

   // the size of the button text in "points"
   private static final float BTN_PTS = 64;

   // starting text for button. Has spaces so button isn't too narrow
   private static final String INITIAL_TEXT = "   ";

   // The 2-D JButton array that holds our buttons
   private JButton[][] buttonGrid = new JButton[MAX_ROWS][MAX_COLS];
   private int buttonPressCount = 0;

   public ButtonGridGuiPanel() {
      JPanel buttonGridPanel = new JPanel(); // jpanel to hold the buttons
      buttonGridPanel.setLayout(new GridLayout(MAX_ROWS, MAX_COLS));

      // create an action listener to add to all buttons
      ButtonListener btnListener = new ButtonListener();

      // iterate through the 2-d button array
      for (int row = 0; row < buttonGrid.length; row++) {
         for (int col = 0; col < buttonGrid[row].length; col++) {
            // create a new button with blank text
            JButton btn = new JButton(INITIAL_TEXT);
            // set its font
            btn.setFont(btn.getFont().deriveFont(Font.BOLD, BTN_PTS));
            // add the action listener
            btn.addActionListener(btnListener);
            buttonGridPanel.add(btn); // add button to the JPanel
            buttonGrid[row][col] = btn; // and add it to the 2-d array
         }
      }

      JButton resetButton = new JButton("Reset");
      resetButton.addActionListener(new ActionListener() {
         @Override
         public void actionPerformed(ActionEvent e) {
            reset(); // call the reset method, that's it!
         }
      });
      JPanel resetBtnPanel = new JPanel(); // to hold reset button
      resetBtnPanel.add(resetButton);

      setLayout(new BorderLayout()); // main JPanel uses border layout
      add(buttonGridPanel, BorderLayout.CENTER); // add button grid panel to main
      add(resetBtnPanel, BorderLayout.PAGE_END); // add reset btn panel to main
   }

   public void reset() {
      buttonPressCount = 0; // in order that first press gives "X"

      // then iterate through the button grid's rows and columns
      // setting button text back to its initial state
      for (int row = 0; row < buttonGrid.length; row++) {
         for (int col = 0; col < buttonGrid[row].length; col++) {
            buttonGrid[row][col].setText(INITIAL_TEXT);
         }
      }
   }

   // a simple action listener that finds out which button has been pressed
   // and sets the button's text alternatingly to "X" or "O"
   private class ButtonListener implements ActionListener {

      @Override
      public void actionPerformed(ActionEvent e) {
         JButton btn = (JButton)e.getSource(); // get pressed button
         String text = btn.getText().trim(); // get its text
         if (text.isEmpty()) { // if text is blank

            // iterate through the 2d button array to find out the 
            // row and col position of the pressed button 
            int rowPressed = -1;
            int colPressed = -1;
            for (int row = 0; row < buttonGrid.length; row++) {
               for (int col = 0; col < buttonGrid[row].length; col++) {
                  if (btn == buttonGrid[row][col]) {
                     // button has been found!
                     rowPressed = row;
                     colPressed = col;
                  }
               }
            }
            // make the button text alternate between X and O 
            text = (buttonPressCount % 2 == 0) ? "X" : "O";
            btn.setText(text); // set the button's text
            buttonPressCount++;

            // TODO: perform whatever logic is necessary based on the row
            // and column position of the button
            System.out.printf("[row, col]: [%d, %d]%n", rowPressed, colPressed);
         }

      }
   }

   private static void createAndShowUI() {
      JFrame frame = new JFrame("Button Grid");
      frame.getContentPane().add(new ButtonGridGuiPanel());
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      // create the GUI in a thread-safe manner
      java.awt.EventQueue.invokeLater(new Runnable() {
         public void run() {
            createAndShowUI();
         }
      });
   }
}

如何通过swing界面中的所有按钮进行迭代？

2 个答案: