Static class for Java related methods
Package: R.utils
Class Java
Object~~|~~+--Java
Directly known subclasses:
public static class Java
extends Object
Static class that provides methods for reading and writing Java data types.
Currently the following data types are supported: byte, short and int.
R character strings can be written as UTF-8 formatted strings, which can
be read by Java. Currently on Java String's that contain ASCII characters
can be imported into R. The reason for this is that other characters are
translated into non-eight bits data, e.g. 16- and 24-bits, which the
readChar() method currently does not support.
Furthermore, the Java class defines some static constants describing the
minimum and maximum value of some of the common Java data types:
BYTE.MIN, BYTE.MAX
SHORT.MIN, SHORT.MAX
INT.MIN, INT.MAX
LONG.MIN, and LONG.MAX.
Java()
Methods:
asByte |
Converts a numeric to a Java byte. | |
asInt |
Converts an numeric to a Java integer. | |
asLong |
Converts a numeric to a Java long. | |
asShort |
Converts a numeric to a Java short. | |
readByte |
Reads a Java formatted byte (8 bits) from a connection. | |
readInt |
Reads a Java formatted int (32 bits) from a connection. | |
readShort |
Reads a Java formatted short (16 bits) from a connection. | |
readUTF |
Reads a Java (UTF-8) formatted string from a connection. | |
writeByte |
Writes a byte (8 bits) to a connection in Java format. | |
writeInt |
Writes a integer (32 bits) to a connection in Java format. | |
writeShort |
Writes a short (16 bits) to a connection in Java format. | |
writeUTF |
Writes a string to a connection in Java format (UTF-8). | |
Methods inherited from Object:
$, $<-, [[, [[<-, as.character, attach, attachLocally, clearCache, clearLookupCache, clone, detach, equals, extend, finalize, getEnvironment, getFieldModifier, getFieldModifiers, getFields, getInstantiationTime, getStaticInstance, hasField, hashCode, ll, load, names, objectSize, print, save
Henrik Bengtsson
pathname <- tempfile()
# Open the temporary file for writing
out <- file(pathname, open="wb")
b <- -128:127
Java$writeByte(out, b)
s <- -32768:32767
Java$writeShort(out, s)
i <- c(-2147483648, -2147483647, -1, 0, +1, 2147483646, 2147483647);
Java$writeInt(out, i)
str <- c("This R string was written (using the UTF-8 format) using",
"the static methods of the Java class in the R.io package.")
str <- paste(str, collapse="\n")
Java$writeUTF(out, str)
close(out)
# Open the temporary file for reading
inn <- file(pathname, open="rb")
bfr <- Java$readByte(inn, n=length(b))
cat("Read ", length(bfr), " bytes.\n", sep="")
if (!identical(bfr, b))
throw("Failed to read the same data that was written.")
bfr <- Java$readShort(inn, n=length(s))
cat("Read ", length(bfr), " shorts.\n", sep="")
if (!identical(bfr, s))
throw("Failed to read the same data that was written.")
bfr <- Java$readInt(inn, n=length(i))
cat("Read ", length(bfr), " ints.\n", sep="")
if (!identical(bfr, i))
throw("Failed to read the same data that was written.")
bfr <- Java$readUTF(inn)
cat("Read ", nchar(bfr), " UTF characters:\n", "'", bfr, "'\n", sep="")
close(inn)
file.remove(pathname)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.