Java text with different colors_in different colors与with different colors-优快云博客

本文链接：https://blog.youkuaiyun.com/bswangjian/article/details/6288023

本文介绍如何利用Java中的JTextPane组件为文本设置不同的颜色。通过具体示例展示了如何为数字添加红色、蓝色及黑色显示效果，并提供了一个完整的程序实例，用于区分质数、完全平方数和其他数字。

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I want to have two lines in red and next two lines in blue color.
Is it possible ?

>> In fact, you can do it with a JTextPane, not a JTextArea.

Here is an example:
===============

import javax.swing.*;
import javax.swing.text.*;
import java.awt.Color;
public class ColorPane extends JTextPane
{
    private static final long serialVersionUID = -6096151257389088124L;
    public void appendNaive(Color c, String s)
    { // naive implementation
        // bad: instantiates a new AttributeSet object on each call
        SimpleAttributeSet aset = new SimpleAttributeSet();
        StyleConstants.setForeground(aset, c);
        int len = getText().length();
        setCaretPosition(len); // place caret at the end (with no selection)
        setCharacterAttributes(aset, false);
        replaceSelection(s); // there is no selection, so inserts at caret
    }
    public void append(Color c, String s)
    { // better implementation--uses StyleContext
        StyleContext sc = StyleContext.getDefaultStyleContext();
        AttributeSet aset = sc.addAttribute(SimpleAttributeSet.EMPTY,
            StyleConstants.Foreground, c);
        int len = getDocument().getLength(); // same value as
        // getText().length();
        setCaretPosition(len); // place caret at the end (with no selection)
        setCharacterAttributes(aset, false);
        replaceSelection(s); // there is no selection, so inserts at caret
    }
    public static void main(String argv[])
    {
        ColorPane pane = new ColorPane();
        for (int n = 1; n <= 400; n += 1)
        {
            if (isPrime(n))
            {
                pane.append(Color.red, String.valueOf(n) + ' ');
            }
            else if (isPerfectSquare(n))
            {
                pane.append(Color.blue, String.valueOf(n) + ' ');
            }
            else
            {
                pane.append(Color.black, String.valueOf(n) + ' ');
            }
        }
        JFrame f = new JFrame("ColorPane example");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setContentPane(new JScrollPane(pane));
        f.setSize(600, 400);
        f.setVisible(true);
    }
    public static boolean isPrime(int n)
    {
        if (n < 2)
            return false;
        double max = Math.sqrt(n);
        for (int j = 2; j <= max; j += 1)
            if (n % j == 0)
                return false; // j is a factor
        return true;
    }
    public static boolean isPerfectSquare(int n)
    {
        int j = 1;
        while (j * j < n && j * j > 0)
            j += 1;
        return (j * j == n);
    }
}

All these are copied from network, not mine :)