guava I/O Handling existing Readers and Writers

Example

Reading the content of a Reader as a String:

// Reading from a file
try (Reader reader = new FileReader("in.txt")) {
  String content = CharStreams.toString(reader);
  // do something with content
}

Reading the content of a Reader as a list of line contents:

try (Reader reader = new FileReader("in.txt")) {
  List<String> lines = CharStreams.readLines(reader);
  for (String line: lines) {
    // Do something with line
  }
}

Copying a Reader to a Writer:

try (Reader reader = new FileReader("in.txt");
     Writer writer = new FileWriter("out.txt")) {
  CharStreams.copy(reader, writer);
}

Note: to copy files directly, it's better to use Files.copy(sourceFile, destinationFile).

Skipping n bytes from the Reader:

try (Reader reader = new FileReader("in.txt")) {
  CharStreams.skipFully(reader, 20);
  // The next char read will be the 21st.
} catch (EOFException e) {
  // There was less than 20 chars in the Reader.
}

Creating a Writer that discards everything that is written to it:

try (Reader reader = new FileReader("in.txt");
     Writer writer = CharStreams.nullWriter()) {
  CharStreams.copy(reader, writer);
  // The whole content of reader is read into... nothing.
}