{"id":12334,"date":"2022-09-30T12:05:11","date_gmt":"2022-09-30T06:35:11","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-removing-ascii-characters-in-a-string-with-encoding\/"},"modified":"2022-09-30T12:05:11","modified_gmt":"2022-09-30T06:35:11","slug":"solved-removing-ascii-characters-in-a-string-with-encoding","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-removing-ascii-characters-in-a-string-with-encoding\/","title":{"rendered":"[Solved] Removing ASCII characters in a string with encoding"},"content":{"rendered":"

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I gave a unsatisfying answer, thanks to @OlegEstekhin for pointing that out.
\nAs noone else answered yet, and a solution is not a two-liner, here it goes.<\/p>\n

Make a wrapping InputStream that throws away escape sequences. I have used a PushbackInputStream, where a partial sequence skipped, may still be pushed back for reading first. Here a FilterInputStream<\/a> would suffice.<\/p>\n

public class EscapeRemovingInputStream extends PushbackInputStream {\n\n    public static void main(String[] args) {\n        String s = \"\\u001B[kHello \\u001B[H12JWorld!\";\n        byte[] buf = s.getBytes(StandardCharsets.ISO_8859_1);\n        ByteArrayInputStream bais = new ByteArrayInputStream(buf);\n        EscapeRemovingInputStream bin = new EscapeRemovingInputStream(bais);\n        try (InputStreamReader in = new InputStreamReader(bin,\n                StandardCharsets.ISO_8859_1)) {\n            int c;\n            while ((c = in.read()) != -1) {\n                System.out.print((char) c);\n            }\n            System.out.println();\n        } catch (IOException ex) {\n            Logger.getLogger(EscapeRemovingInputStream.class.getName()).log(\n                Level.SEVERE, null, ex);\n        }\n    }\n\n    private static final Pattern ESCAPE_PATTERN = Pattern.compile(\n        \"\\u001B\\\\[(k|m|H\\\\d+J|\\\\d+:\\\\d+H|\\\\?\\\\d+\\\\w|\\\\d*i)\");\n    private static final int MAX_ESCAPE_LENGTH = 20;\n\n    private final byte[] escapeSequence = new byte[MAX_ESCAPE_LENGTH];\n    private int escapeLength = 0;\n    private boolean eof = false;\n\n    public EscapeRemovingInputStream(InputStream in) {\n        this(in, MAX_ESCAPE_LENGTH);\n    }\n\n    @Override\n    public int read(byte[] b, int off, int len) throws IOException {\n        for (int i = 0; i < len; ++i) {\n            int c = read();\n            if (c == -1) {\n                return i == 0 ? -1 : i;\n            }\n            b[off + i] = (byte) c;\n        }\n        return len;\n    }\n\n    @Override\n    public int read() throws IOException {\n        int c = eof ? -1 : super.read();\n        if (c == -1) { \/\/ Throw away a trailing half escape sequence.\n            eof = true;\n            return c;\n        }\n        if (escapeLength == 0 && c != 0x1B) {\n            return c;\n        } else {\n            escapeSequence[escapeLength] = (byte) c;\n            ++escapeLength;\n            String esc = new String(escapeSequence, 0, escapeLength,\n                    StandardCharsets.ISO_8859_1);\n            if (ESCAPE_PATTERN.matcher(esc).matches()) {\n                escapeLength = 0;\n            } else if (escapeLength == MAX_ESCAPE_LENGTH) {\n                escapeLength = 0;\n                unread(escapeSequence);\n                return super.read(); \/\/ No longer registering the escape\n            }\n            return read();\n        }\n    }\n\n}\n<\/code><\/pre>\n