java - 从内部类引用

Question

我有以下代码

import javax.swing.*;
import java.awt.*;
import net.miginfocom.swing.MigLayout;
import Sorts.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.awt.Color;

public class SortsGui
{
    JFrame myMainWindow = new JFrame("Sorts");

    JPanel sortPanel = new JPanel();

    //first panel components
    public int nextTextBox = 20;
    JTextField[] allField = new JTextField [25];
    //end first panel

    public void runGUI()
    {
        myMainWindow.setBounds(10, 10, 800, 800);
        myMainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        myMainWindow.setLayout(new GridLayout(1,1));

        createSortTestPanel();

        myMainWindow.getContentPane().add(sortPanel);

        myMainWindow.setVisible(true);
    }

    public void createSortTestPanel()
    {
        MigLayout layout = new MigLayout("" , "[grow]");
        sortPanel.setLayout(layout);

        refreshScreen();
    }

    public void refreshScreen()
    {
        sortPanel.removeAll();

        for(int i = 0; i<nextTextBox;i++)
        {
            int fix = i+1;
            allField[i] = new JTextField("");
            sortPanel.add(allField[i],"growx");
            allField[i].addKeyListener(new KeyListener ()
            {
                public void keyPressed(KeyEvent e)
                {

                }

                public void keyReleased(KeyEvent e)
                {

                }

                public void keyTyped(KeyEvent e)
                {
                    char c = e.getKeyChar();
                    if(Character.isDigit(c))
                    {

                    }

                    else 
                    {
                        e.consume();
                    }

                    try
                    {
                        int parseTest = Integer.parseInt(allField[i].getText());
                    }

                    catch(Exception exc)
                    {
                        allField[i].setBackground(Color.RED);
                    }
                }
            });
        }
    }

    public static void main(String[] args)
    {
        SortsGui sG = new SortsGui();
        sG.runGUI();
    }
}

我的目标是创建一个具有按键监听器的 JTextField 数组。此键监听器应阻止在 JTextField 中输入除数字之外的任何内容。如果输入的数字不是 int，它还应该更改 JTextField 背景的颜色。例如 2147483647554。 但是，当我编译这个时，我收到错误

那么我该如何使其成为所有 JTextField 上的最终或有效最终？

Answer 1

My aim here is to create an array of JTextFields which have a keylistener on. This keylistener should prevent anything other than numbers being entered in the JTextField

对此问题的简短回答是，不要使用KeyListener，它不会捕获用户将文本粘贴到字段中或以编程方式更新字段的用例

例如，您想使用DocumentFilter

public class IntFilter extends DocumentFilter {

    @Override
    public void insertString(DocumentFilter.FilterBypass fb, int offset, String text, AttributeSet attr) throws BadLocationException {

        StringBuilder buffer = new StringBuilder(text.length());
        for (int index = 0; index < text.length(); index++) {
            if (Character.isDigit(text.charAt(index))) {
                buffer.append(text.charAt(index));
            }
        }
        super.insertString(fb, offset, buffer.toString(), attr);
        ValidationListener listener = getValidationListener();
    }

    @Override
    public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String string, AttributeSet attr) throws BadLocationException {
        if (length > 0) {
            fb.remove(offset, length);
        }
        insertString(fb, offset, string, attr);
    }
}

参见Implementing a Document Filter了解更多详情和 DocumentFilter Examples更多示例

It should also change the color of the JTextField's background if the number entered is not an int

您可以使用 InputVerifier 进行后验证，但这可能无法满足您的需求。

这会产生一个问题。 DocumentFilter 不应该关心它所应用的字段，但是由于它正在执行验证，因此它会知道何时出现问题，因此我们需要某种方式让过滤器在出现问题时提供通知验证失败...

首先，我们需要一些回调来告诉我们验证何时失败或通过......

public interface ValidationListener {

    public void validationFailed();

    public void validationPassed();
}

然后我们需要更新过滤器以根据其规则发出这些通知...

public class IntFilter extends DocumentFilter {

    private ValidationListener validationListener;

    public void setValidationListener(ValidationListener validationListener) {
        this.validationListener = validationListener;
    }

    public ValidationListener getValidationListener() {
        return validationListener;
    }

    @Override
    public void insertString(DocumentFilter.FilterBypass fb, int offset, String text, AttributeSet attr) throws BadLocationException {

        boolean validationFailed = false;
        StringBuilder buffer = new StringBuilder(text.length());
        for (int index = 0; index < text.length(); index++) {
            if (Character.isDigit(text.charAt(index))) {
                buffer.append(text.charAt(index));
            } else {
                validationFailed = true;
            }
        }
        super.insertString(fb, offset, buffer.toString(), attr);
        ValidationListener listener = getValidationListener();
        if (listener != null) {
            if (validationFailed) {
                listener.validationFailed();
            } else {
                listener.validationPassed();
            }
        }
    }

    @Override
    public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String string, AttributeSet attr) throws BadLocationException {
        if (length > 0) {
            fb.remove(offset, length);
        }
        insertString(fb, offset, string, attr);
    }
}

然后我们需要定义 ValidationListener 的实现来执行我们需要的操作...

public class DefaultValidationHandler implements ValidationListener {

    private JTextField field;

    public DefaultValidationHandler(JTextField field) {
        this.field = field;
    }

    public JTextField getField() {
        return field;
    }

    @Override
    public void validationFailed() {
        getField().setBackground(Color.RED);
    }

    @Override
    public void validationPassed() {
        getField().setBackground(UIManager.getColor("TextField.background"));
    }

}

这里，监听器维护了对我们想要控制的字段的引用

然后我们将其完全绑定(bind)...

JTextField field = new JTextField(10);
DefaultValidationHandler handler = new DefaultValidationHandler(field);
IntFilter filter = new IntFilter();
filter.setValidationListener(handler);
((AbstractDocument)field.getDocument()).setDocumentFilter(filter);

这有点粗糙，但它传达了基本思想。

一些改进可能包括通过 ValidationListener 的方法传回 DocumentFilter 的引用，然后您可以使用它来查找触发事件并更新的字段例如，减少您可能需要创建的处理程序的数量。

例如

更新了 ValidationListener

public interface ValidationListener {

    public void validationFailed(DocumentFilter filter);

    public void validationPassed(DocumentFilter filter);
}

更新了 IntFilter

public class IntFilter extends DocumentFilter {

    private ValidationListener validationListener;

    public void setValidationListener(ValidationListener validationListener) {
        this.validationListener = validationListener;
    }

    public ValidationListener getValidationListener() {
        return validationListener;
    }

    @Override
    public void insertString(DocumentFilter.FilterBypass fb, int offset, String text, AttributeSet attr) throws BadLocationException {

        boolean validationFailed = false;
        StringBuilder buffer = new StringBuilder(text.length());
        for (int index = 0; index < text.length(); index++) {
            if (Character.isDigit(text.charAt(index))) {
                buffer.append(text.charAt(index));
            } else {
                validationFailed = true;
            }
        }
        super.insertString(fb, offset, buffer.toString(), attr);
        ValidationListener listener = getValidationListener();
        if (listener != null) {
            if (validationFailed) {
                listener.validationFailed(this);
            } else {
                listener.validationPassed(this);
            }
        }
    }

    @Override
    public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String string, AttributeSet attr) throws BadLocationException {
        if (length > 0) {
            fb.remove(offset, length);
        }
        insertString(fb, offset, string, attr);
    }
}

示例实现...

public class TestPane extends JPanel {

    private Map<DocumentFilter, JTextField> fields;

    public TestPane() {

        fields = new HashMap<>(25);
        ValidationListener listener = new ValidationListener() {

            @Override
            public void validationFailed(DocumentFilter filter) {
                JTextField field = fields.get(filter);
                if (field != null) {
                    field.setBackground(Color.RED);
                }
            }

            @Override
            public void validationPassed(DocumentFilter filter) {
                JTextField field = fields.get(filter);
                if (field != null) {
                    field.setBackground(UIManager.getColor("TextField.background"));
                }
            }
        };

        setLayout(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        for (int index = 0; index < 10; index++) {
            JTextField field = new JTextField(10);
            IntFilter filter = new IntFilter();
            filter.setValidationListener(listener);
            ((AbstractDocument) field.getDocument()).setDocumentFilter(filter);
            fields.put(filter, field);
            add(field, gbc);
        }

    }

}