将用户输入的前景色应用到 JTextArea？为什么字符串前景色不起作用？

Question

import java.applet.Applet;
import java.awt.*;
import java.util.Scanner;
import javax.swing.*;

public class font_chooser extends JApplet {

    public static void main(String[] args) {

        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        Object[] possibilities = ge.getAvailableFontFamilyNames();
        Object[] colors = { "red", "yellow", "blue", "orange", "pink", "cyan", "magenta", "black", "white", "gray" };
        String font = (String) JOptionPane.showInputDialog(null, "Choose a Font", "Font Chooser",
                +JOptionPane.PLAIN_MESSAGE, null, possibilities, "");

我将变量 foregroundcolor 设置为用户输入

        String foregroundcolor = (String) JOptionPane.showInputDialog(null, "Chose Font Color", "Color",
                JOptionPane.PLAIN_MESSAGE, null, colors, "");

如果用户正确选择字体和颜色，我将打印此 pangram

        if ((font != null) && (font.length() > 0) && (colors != null)) {
            JTextArea textArea = new JTextArea("The quick brown fox jumped over the lazy dog’s back."
                    + "\n Pack my box with five dozen liquor jugs" + "\n Jackdaws love my big sphinx of quartz."
                    + "\n Mr. Jock, TV quiz PhD, bags few lynx." + "\n abcdefghijklmnopqrstuvwxyz"
                    + "\n ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "\n 01234567890"
                    + "\n €†™´¸¢©¤°÷½¼¾>¡¿«‘’<¯µ ·¬ªº¶±£\"»®§­¹²³ß×™¥" + "\n ÀÁÂÃÄÅÆÇÈÉ ÊËÌÍÎÏÐÑÒÓÔ ÕÖØÙÚÛÜÝÞÿ"
                    + "\n àáâãäåæçèé êëìíîïðñòóô õöøùúûüýþÿ" + "\n !\"#$%&'()*+,-./:;<=>?@[\\^_z{|}~"
                    + "\n uvw wW gq9 2z 5s il17|!j oO08 `'\" ;:,. m nn rn {[()]}u");
            textArea.setFont(new Font((String) font, Font.ITALIC, 16));

我将 textArea 前景应用到用户输入，这似乎不能正常工作，你想吗？

            textArea.setForeground(Color.getColor(foregroundcolor));
            JOptionPane.showMessageDialog(null, textArea);
            // JOptionPane.showMessageDialog(null, "You chose " + font);
        }
    }

}

Answer 1

您误解了Color.getColor(...) 方法。它需要一个字符串，但它是颜色 int 的字符串表示形式，而不是颜色字符串的字符串表示形式。根据颜色 API：

参数被视为要获取的系统属性的名称。此属性的字符串值随后被解释为一个整数，然后将其转换为一个 Color 对象。

考虑使用Map<String, Color> 来帮助您设置颜色。

例如（虽然丑陋，因为它使用并行数组：

import java.awt.*;
import java.util.HashMap;
import java.util.Map;

import javax.swing.*;

public class TestColors {
    public static void main(String[] args) {

        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        Object[] possibilities = ge.getAvailableFontFamilyNames();
        String[] colors = { "red", "yellow", "blue", "orange", "pink", "cyan", "magenta", "black", "white", "gray" };
        Color[] realColors = { Color.RED, Color.YELLOW, Color.BLUE, Color.ORANGE, Color.PINK, Color.CYAN, Color.MAGENTA,
                Color.BLACK, Color.WHITE, Color.GRAY };
        Map<String, Color> colorMap = new HashMap<>();
        for (int i = 0; i < colors.length; i++) {
            colorMap.put(colors[i], realColors[i]);
        }
        String font = (String) JOptionPane.showInputDialog(null, "Choose a Font", "Font Chooser",
                +JOptionPane.PLAIN_MESSAGE, null, possibilities, "");

        String foregroundcolor = (String) JOptionPane.showInputDialog(null, "Chose Font Color", "Color",
                JOptionPane.PLAIN_MESSAGE, null, colors, "");
        System.out.println(foregroundcolor);

        if ((font != null) && (font.length() > 0) && (colors != null)) {
            JTextArea textArea = new JTextArea("The quick brown fox jumped over the lazy dog’s back."
                    + "\n Pack my box with five dozen liquor jugs" + "\n Jackdaws love my big sphinx of quartz."
                    + "\n Mr. Jock, TV quiz PhD, bags few lynx." + "\n abcdefghijklmnopqrstuvwxyz"
                    + "\n ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "\n 01234567890"
                    + "\n €†™´¸¢©¤°÷½¼¾>¡¿«‘’<¯µ ·¬ªº¶±£\"»®§­¹²³ß×™¥" + "\n ÀÁÂÃÄÅÆÇÈÉ ÊËÌÍÎÏÐÑÒÓÔ ÕÖØÙÚÛÜÝÞÿ"
                    + "\n àáâãäåæçèé êëìíîïðñòóô õöøùúûüýþÿ" + "\n !\"#$%&'()*+,-./:;<=>?@[\\^_z{|}~"
                    + "\n uvw wW gq9 2z 5s il17|!j oO08 `'\" ;:,. m nn rn {[()]}u");
            textArea.setFont(new Font((String) font, Font.ITALIC, 16));

            textArea.setForeground(colorMap.get(foregroundcolor));
            JOptionPane.showMessageDialog(null, new JScrollPane(textArea));
            // JOptionPane.showMessageDialog(null, "You chose " + font);
        }
    }
}

注意

1. 如果您的类不用作小程序，则不应扩展 JApplet。
2. 现在什么都不应该使用小程序了。

干净一点：

import java.awt.*;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.swing.*;

public class TestColors {
    public static void main(String[] args) {

        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        Object[] possibilities = ge.getAvailableFontFamilyNames();
        Map<String, Color> myColorMap = new LinkedHashMap<>();
        myColorMap.put("Red", Color.RED);
        myColorMap.put("Orange", Color.ORANGE);
        myColorMap.put("Yellow", Color.YELLOW);
        myColorMap.put("Green", Color.GREEN);
        myColorMap.put("Blue", Color.BLUE);
        myColorMap.put("Magenta", Color.MAGENTA);
        myColorMap.put("Black", Color.BLACK);
        myColorMap.put("Gray", Color.GRAY);

        String[] myColors = myColorMap.keySet().toArray(new String[] {});
        String font = (String) JOptionPane.showInputDialog(null, "Choose a Font", "Font Chooser",
                +JOptionPane.PLAIN_MESSAGE, null, possibilities, "");

        String foregroundcolor = (String) JOptionPane.showInputDialog(null, "Chose Font Color", "Color",
                JOptionPane.PLAIN_MESSAGE, null, myColors, "");

        if ((font != null) && (font.length() > 0) && (foregroundcolor != null)) {
            JTextArea textArea = new JTextArea("The quick brown fox jumped over the lazy dog’s back."
                    + "\n Pack my box with five dozen liquor jugs" + "\n Jackdaws love my big sphinx of quartz."
                    + "\n Mr. Jock, TV quiz PhD, bags few lynx." + "\n abcdefghijklmnopqrstuvwxyz"
                    + "\n ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "\n 01234567890"
                    + "\n €†™´¸¢©¤°÷½¼¾>¡¿«‘’<¯µ ·¬ªº¶±£\"»®§­¹²³ß×™¥" + "\n ÀÁÂÃÄÅÆÇÈÉ ÊËÌÍÎÏÐÑÒÓÔ ÕÖØÙÚÛÜÝÞÿ"
                    + "\n àáâãäåæçèé êëìíîïðñòóô õöøùúûüýþÿ" + "\n !\"#$%&'()*+,-./:;<=>?@[\\^_z{|}~"
                    + "\n uvw wW gq9 2z 5s il17|!j oO08 `'\" ;:,. m nn rn {[()]}u");
            textArea.setFont(new Font((String) font, Font.ITALIC, 16));

            textArea.setForeground(myColorMap.get(foregroundcolor));
            JOptionPane.showMessageDialog(null, new JScrollPane(textArea));
        }
    }
}