How do I display tabs with spaces?

I have a java program that draws each character (in its own frame) from a text file on a JPanel with a grid

Code of drawing text:

g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
Font font = new Font("monospaced",Font.PLAIN,18);
g2.setColor(Color.BLACK);
g2.setFont(font);
String lines[] = LabAgentComponent.PASTE.split("\\r?\\n");
for (int i=0; i<lines.length; i++) {
    for(int j=0; j<lines[i].length(); j++) {
        g2.drawString(Character.toString(lines[i].charAt(j)),j * gridSize,(i+1) * gridSize);
    }
}

Solution

You can check the length of the string before the tab

In the case of Al203, that would be 5 Your label should start with the next multiple of 8 with at least one space between them

This is a small class that can help you:

public class TabToSpaces
{
    public static void main(String[] args) {
        System.out.println(replaceTab("\tb",8,"."));
        System.out.println(replaceTab("a\tb","."));
        System.out.println(replaceTab("abcdefg\th","."));
        System.out.println(replaceTab("abcdefgh\ti","."));
        System.out.println(replaceTab("a\tb\tc\td\te","."));
        System.out.println(replaceTab("ab\tb\tc\td\te","."));
    }

    private static String replaceTab(String string,int tabSize,String space) {
        Pattern pattern = Pattern.compile("\t");
        Matcher matcher = pattern.matcher(string);
        StringBuffer sb = new StringBuffer();
        int offset = 0;
        while (matcher.find()) {
            int beforeLength = matcher.start() + offset;
            int spacesNeeded = (int) (Math.ceil((beforeLength + 1.0) / tabSize) * tabSize) - beforeLength;
            offset += spacesNeeded - 1;
            String spaces = new String(new char[spacesNeeded]).replace("\0",space);
            matcher.appendReplacement(sb,spaces);
        }
        matcher.appendTail(sb);
        return sb.toString();
    }
}

It outputs:

........b
a.......b
abcdefg.h
abcdefgh........i
a.......b.......c.......d.......e
ab......b.......c.......d.......e

I use dots to make the space clearer