Class CompactOneLineFormatter

java.lang.Object
java.util.logging.Formatter
zeroecho.logging.CompactOneLineFormatter
public final class CompactOneLineFormatter extends Formatter
A compact single-line Formatter for JUL log records.

Each record is rendered into one line containing:

  • timestamp in yyyy-MM-dd HH:mm:ss.SSS format (local time zone),
  • log level name,
  • current thread name,
  • source class and method (abbreviated),
  • the formatted message with whitespace collapsed,
  • and, if present, exception information: exception type, message, and first stack frame, rendered inline.

This formatter is designed for console or file logs where compactness and readability in a single line per record are preferred over multi-line stack traces. Exception stack traces are summarized to avoid overwhelming output; only the first frame is shown.

Example output

2025-09-10 22:15:32.184 INFO [main] c.e.d.p.MyService#start - Started service
2025-09-10 22:15:33.201 SEVERE [worker-1] c.e.d.p.Worker#run - Task failed
  | ex=IllegalStateException: bad state @ Worker.java:42

Abbreviation rules

  • Package names are reduced to their initials (e.g., com.example.deep.package.MyService → c.e.d.p.MyService).
  • Simple class names are shortened by keeping uppercase letters before the last uppercase, and then the last uppercase plus the suffix (e.g., MyServiceManager → MSManager, XmlHttpRequest → XHR, UserDAO → UDAO, FooBar → FBar).
Since:
1.0

  • Constructor Details

    • CompactOneLineFormatter

      public CompactOneLineFormatter()
      Creates a formatter using the system time zone for timestamps.

  • Method Details

    • format

      public String format(LogRecord r)
      Formats a LogRecord into a single line.

      The message text has runs of whitespace collapsed to a single space. If LogRecord.getThrown() is non-null, the formatter appends a compact suffix in the form " | ex=<Type>: <message> @ <firstStackFrame>".

      Specified by:
      format in class Formatter
      Parameters:
      r - the log record to format
      Returns:
      formatted line ending with the platform line separator