无法将 JScrollPane 添加到 JTextArea

Question

我搜索了一半的互联网，但找不到遇到同样问题的人。

我尝试了几种不同的方法来添加垂直滚动条，但都没有用。我见过的每个 post 描述此问题的人都做了以下事情：

    JTextArea ta = new JTextArea();
    JScrollPane sc = new JScrollPane(ta);

这似乎对他们有用。但我运气不好，已经尝试了至少 30 种我发现的不同方法。我是 java 的新手，我所在的 class 快要死了。谢谢你的时间。

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Gui extends JFrame
private JTextArea outputArea {
    private JButton eastButton;
    private JButton westButton;
    private JButton northButton;
    private JButton southButton;
    private JButton helpButton;
    private JButton pickupButton;
    private JButton dropButton;
    private JButton eatButton;
    private JButton lookButton;
    private JButton listButton;
    private JScrollPane scroll;
    Gui() {
        int x = 0;
        int y = 0;
        int Width = 1;
        int Height = 2;
        int anchor;
        GridBagConstraints gbc = new GridBagConstraints();
        JLabel actionsLabel = null;
        JLabel directionsLabel = null;
        getContentPane().setBackground(Color.black);
        setTitle("Castle Quest");
        actionsLabel = new JLabel("Actions");
        actionsLabel.setForeground(Color.red);
        directionsLabel = new JLabel("Directions");
        directionsLabel.setForeground(Color.red);
        outputArea = new JTextArea(25, 35);
        scroll = new JScrollPane(outputArea);
        eastButton = new JButton("east");
        eastButton.setSize(100, 30);
        westButton = new JButton("west");
        westButton.setSize(100, 30);
        northButton = new JButton("north");
        northButton.setSize(100, 30);
        southButton = new JButton("south");
        southButton.setSize(100, 30);
        helpButton = new JButton("help");
        helpButton.setSize(100, 30);
        pickupButton = new JButton("pickup");
        pickupButton.setSize(100, 30);
        dropButton = new JButton("Drop");
        dropButton.setSize(100, 30);
        eatButton = new JButton("eat");
        lookButton = new JButton("look");
        lookButton.setSize(100, 30);
        listButton = new JButton("list");
        listButton.setSize(100, 30);
        outputArea.setEditable(true);
        GridBagLayout gbl = new GridBagLayout();
        setLayout(gbl);
        gbc.insets = new Insets(10, 10, 10, 10);
        gbc.gridx = 1;
        gbc.gridy = 1;
        gbc.gridwidth = 1;
        gbc.gridheight = 2;
        gbc.anchor = GridBagConstraints.NORTHWEST;
        add(actionsLabel, gbc);
        gbc.gridy += 2;
        add(helpButton, gbc);
        gbc.gridy += 2;
        add(pickupButton, gbc);
        gbc.gridy += 2;
        add(dropButton, gbc);
        gbc.gridy += 2;
        add(eatButton, gbc);
        gbc.gridy += 2;
        add(lookButton, gbc);
        gbc.gridy += 2;
        add(listButton, gbc);
        gbc.gridy = 1;
        gbc.gridx = 2;
        gbc.gridheight = 50;
        outputArea.setBackground(Color.red);
        add(outputArea, gbc);
        gbc.gridheight = 2;
        gbc.gridx = 3;
        gbc.gridy = 1;
        add(directionsLabel, gbc);
        gbc.gridy = 3;
        add(eastButton, gbc);
        gbc.gridy += 2;
        add(westButton, gbc);
        gbc.gridy += 2;
        add(northButton, gbc);
        gbc.gridy += 2;
        add(southButton, gbc);
        gbc.gridx = 0;
        gbc.gridy = 1;
    }
    public static void main(String[] args) {
        Gui newGame = new Gui();
        Game funTime = new Game();
        newGame.setSize(400, 150);
        newGame.setBackground(Color.black);
        newGame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        newGame.pack();
        newGame.setVisible(true);
        newGame.outputArea.setLineWrap(true);
        newGame.outputArea.setWrapStyleWord(true);
        newGame.outputArea.append(funTime.getMessage() + "\n");
        newGame.eastButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                funTime.move("east");
                newGame.outputArea.append(funTime.getMessage() + "\n");
            }
        });
        newGame.westButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                funTime.move("west");
                newGame.outputArea.append(funTime.getMessage() + "\n");
            }
        });
        newGame.northButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                funTime.move("north");
                newGame.outputArea.append(funTime.getMessage() + "\n");
            }
        });
        newGame.southButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                funTime.move("south");
                newGame.outputArea.append(funTime.getMessage() + "\n");
            }
        });
        newGame.helpButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                funTime.getHelp();
                newGame.outputArea.append(funTime.getMessage() + "\n");
            }
        });
        newGame.pickupButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (funTime.currentLocation.hasItem()) {
                    funTime.pickupItem();
                    newGame.outputArea.append(funTime.getMessage() + "\n");
                }
            }
        });
        newGame.listButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                for (int i = 0; i < funTime.items.size(); i++) {
                    System.out.println(funTime.items.get(i));
                }
                System.out.println(funTime.items);
                System.out.println(funTime.currentLocation.getRoomItem1() + " & " + funTime.currentLocation.getRoomItem2());
            }
        });
    }
}

Answer 1

您遇到的问题（JTextArea 扩展）是由于您将 JTextArea 添加到容器而不是 JScrollPane。

以下是您应该做的事情背后的逻辑：

JTextArea 包含在 JScrollPane 中，JScrollPane 包含在 JFrame 中。

更改此行

add(outputArea, gbc);

至此

add(scroll, gbc);