clojure.java.io/reader

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Type: function Added: Clojure 1.2 Examples: 3 Runnable: 0

([x & opts])

Attempts to coerce its argument into an open java.io.Reader. Default implementations always return a java.io.BufferedReader.

Default implementations are provided for Reader, BufferedReader, InputStream, File, URI, URL, Socket, byte arrays, character arrays, and String.

If argument is a String, it tries to resolve it first as a URI, then as a local file name. URIs with a 'file' protocol are converted to local file names.

Should be used inside with-open to ensure the Reader is properly closed.

Examples

by steveminer on 2010-11-21 . May have evaluation errors. ▶

(with-open [rdr (clojure.java.io/reader "/tmp/foo.txt")] (into [] (line-seq rdr)))

by jafingerhut on 2011-12-19 . May have evaluation errors. ▶

(with-open [rdr (clojure.java.io/reader "http://www.google.com")] (printf "%s\n" (clojure.string/join "\n" (line-seq rdr)))) ;; <!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" ... ;;=> nil

by reborg on 2019-06-20 . May have evaluation errors. ▶

;; Sometimes it's useful to create a reader from a string, but strings ;; are locations for "reader", so we turn them into char-arrays first: (require '[clojure.java.io :as io]) (with-open [r (io/reader (char-array "hello"))] (slurp r)) ;; "hello"

Note by roryokane

Java documentation links for the listed argument types that have “default implementations�:

• Reader
• BufferedReader
• InputStream
• File
• URI
• URL
• Socket
• byte arrays (byte[])
• character arrays (char[])
• String (resolved as a URI or a local file name)

Note by jakubholynet

opts depend on the type of the reader but common ones include :encoding and, where applicable, :buffer-size.

Note by KingMob

Warning, it does not work with java.nio.file.Path (as of 1.11.1).

See also

• clojure.java.io/writer (1)
• clojure.java.io/input-stream
• clojure.java.io/IOFactory
• clojure.core/slurp (2)

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