Java File I/O Compiler
Modern Java file I/O uses java.nio.file. The example below writes and reads a file in /tmp — the only writable directory in the sandbox. Edit and run live.
Run Java File I/O Compiler examples in the Java compiler
Examples included
Practical tips
- Only /tmp is writable in the sandbox. Use Path.of("/tmp/yourfile.txt").
- Files.writeString and Files.readString are the modern, simplest API (Java 11+).
- Always wrap file ops in try-with-resources or handle IOException.
Common questions
Can I write files in this online Java compiler?
Yes — to /tmp only. Other paths are read-only in the sandbox.
Does my file persist?
No. The sandbox resets after each run. Files are gone immediately after.
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