Writing Files in Groovy

Here’s the translation of the Go code to Groovy, formatted in Markdown for Hugo:

Writing files in Groovy follows similar patterns to the ones we saw earlier for reading.

import groovy.io.FileType

def check(Exception e) {
    if (e != null) {
        throw e
    }
}

// To start, here's how to dump a string (or just bytes) into a file.
def d1 = "hello\ngroovy\n"
try {
    new File("/tmp/dat1").text = d1
} catch (Exception e) {
    check(e)
}

// For more granular writes, open a file for writing.
def f = new File("/tmp/dat2")
f.createNewFile()

// It's idiomatic to use a try-with-resources block to ensure the file is closed
try (def writer = f.newWriter()) {
    // You can write byte arrays as you'd expect.
    def d2 = [115, 111, 109, 101, 10] as byte[]
    def n2 = writer.write(new String(d2))
    println "wrote ${n2} bytes"

    // A write method for strings is also available.
    def n3 = writer.write("writes\n")
    println "wrote ${n3} bytes"

    // Flush writes to ensure they're written to the file.
    writer.flush()

    // BufferedWriter provides buffered writers in addition to the buffered readers we saw earlier.
    def bufferedWriter = new BufferedWriter(writer)
    def n4 = bufferedWriter.write("buffered\n")
    println "wrote ${n4} bytes"

    // Use flush to ensure all buffered operations have been applied to the underlying writer.
    bufferedWriter.flush()
}

Try running the file-writing code.

$ groovy writing-files.groovy
wrote 5 bytes
wrote 7 bytes
wrote 9 bytes

Then check the contents of the written files.

$ cat /tmp/dat1
hello
groovy
$ cat /tmp/dat2
some
writes
buffered

Next we’ll look at applying some of the file I/O ideas we’ve just seen to the stdin and stdout streams.

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Title here

Writing Files in Groovy