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groovyfilehandle

Unclosed file handle when filtering file lines

I've noticed that following code snippet in Groovy lefts unclosed file handle in JVM. I cannot remove this file until GC runs and closes resource by invoking finalizer.

StringWriter writer = new StringWriter()
new File("file.txt").filterLine(writer) { it.startsWith("a") }
println writer.toString()

How to properly close the file when filtering its lines?

Solution

  • filterLine works on a reader too, so you can do:

    StringWriter writer = new StringWriter()
new File("file.txt").withReader { r ->
   r.filterLine(writer) { it.startsWith("a") }
}
println writer.toString()

    withReader closes the reader afterwards