Summary

Add two new methods to java.io.Reader to read all remaining characters in the stream: readAllLines and readAllAsString.

Problem

There are no methods defined by Reader to read the remaining characters as either a list of strings or as a single string. There are readAllBytes methods defined in java.io.InputStream and java.nio.file.Files. Files also defines a readAllLines method to read all characters as a list of lines, and a readString method to read all characters as a String.

Solution

Define two new methods on Reader, readAllLines and readAllAsString, to read all remaining characters as a sequence of lines or as a single string, respectively.

Specification

--- a/src/java.base/share/classes/java/io/Reader.java
+++ b/src/java.base/share/classes/java/io/Reader.java
@@ -382,6 +396,111 @@
 [...]
+
+    /**
+     * Reads all remaining characters as lines of text. This method blocks until
+     * all remaining characters have been read and end of stream is detected,
+     * or an exception is thrown. This method does not close the reader.
+     *
+     * <p> When this reader reaches the end of the stream, further
+     * invocations of this method will return an empty list.
+     *
+     * <p> A <i>line</i> is either a sequence of zero or more characters
+     * followed by a line terminator, or it is a sequence of one or
+     * more characters followed by the end of the stream.
+     * A line does not include the line terminator.
+     *
+     * <p> A <i>line terminator</i> is one of the following:
+     * a line feed character {@code "\n"} (U+000A),
+     * a carriage return character {@code "\r"} (U+000D),
+     * or a carriage return followed immediately by a line feed
+     * {@code "\r\n"} (U+000D U+000A).
+     *
+     * <p> The behavior for the case where the reader is
+     * <i>asynchronously closed</i>, or the thread interrupted during the
+     * read, is highly input reader specific, and therefore not specified.
+     *
+     * <p> If an I/O error occurs reading from the stream, then it
+     * may do so after some, but not all, characters have been read.
+     * Consequently the stream may not be at end of stream and may
+     * be in an inconsistent state. It is strongly recommended that the reader
+     * be promptly closed if an I/O error occurs.
+     *
+     * @apiNote
+     * This method is intended for simple cases where it is convenient
+     * to read all remaining characters in a single operation. It is not
+     * intended for reading a large number of characters, for example,
+     * greater than {@code 1G}.
+     *
+     * @return     the remaining characters as lines of text stored in an
+     *             unmodifiable {@code List} of {@code String}s in the order
+     *             they are read
+     *
+     * @throws     IOException  If an I/O error occurs
+     * @throws     OutOfMemoryError  If the number of remaining characters
+     *             exceeds the implementation limit for {@code String}.
+     *
+     * @see String#lines
+     * @see #readAllAsString
+     * @see java.nio.file.Files#readAllLines
+     *
+     * @since 25
+     */
+    public List<String> readAllLines() throws IOException {}
[...]
+
+    /**
+     * Reads all remaining characters into a string. This method blocks until
+     * all remaining characters including all line separators have been read
+     * and end of stream is detected, or an exception is thrown. The resulting
+     * string will contain line separators as they appear in the stream. This
+     * method does not close the reader.
+     *
+     * <p> When this reader reaches the end of the stream, further
+     * invocations of this method will return an empty string.
+     *
+     * <p> The behavior for the case where the reader
+     * is <i>asynchronously closed</i>, or the thread interrupted during the
+     * read, is highly input reader specific, and therefore not specified.
+     *
+     * <p> If an I/O error occurs reading from the stream, then it
+     * may do so after some, but not all, characters have been read.
+     * Consequently the stream may not be at end of stream and may
+     * be in an inconsistent state. It is strongly recommended that the reader
+     * be promptly closed if an I/O error occurs.
+     *
+     * @apiNote
+     * This method is intended for simple cases where it is appropriate and
+     * convenient to read all remaining characters into a {@code String}. It
+     * is not intended for reading a large number of characters, for example,
+     * greater than {@code 1G}.
+     *
+     * @return     a {@code String} containing all remaining characters
+     *
+     * @throws     IOException       If an I/O error occurs
+     * @throws     OutOfMemoryError  If the number of remaining characters
+     *                               exceeds the implementation limit for
+     *                               {@code String}.
+     *
+     * @see #readAllLines
+     * @see java.nio.file.Files#readString
+     *
+     * @since 25
+     */
+    public String readAllAsString() throws IOException {}