Below is the syntax highlighted version of BinaryStdIn.java
from § Standard Libraries.
Here is the Javadoc.
/************************************************************************* * Compilation: javac BinaryStdIn.java * Execution: java BinaryStdIn < input > output * * Supports reading binary data from standard input. * * % java BinaryStdIn < input.jpg > output.jpg * % diff input.jpg output.jpg * *************************************************************************/ import java.io.IOException; import java.io.BufferedInputStream; /** * <i>Binary standard input</i>. This class provides methods for reading * in bits from standard input, either one bit at a time (as a <tt>boolean</tt>), * 8 bits at a time (as a <tt>byte</tt> or <tt>char</tt>), * 16 bits at a time (as a <tt>short</tt>), 32 bits at a time * (as an <tt>int</tt> or <tt>float</tt>), or 64 bits at a time (as a * <tt>double</tt> or <tt>long</tt>). * <p> * All primitive types are assumed to be represented using their * standard Java representations, in big-endian (most significant * byte first) order. * <p> * The client should not intermix calls to <tt>BinaryStdIn</tt> with calls * to <tt>StdIn</tt> or <tt>System.in</tt>; * otherwise unexpected behavior will result. */ public class BinaryStdIn { private static BufferedInputStream in = new BufferedInputStream(System.in); private static final int EOF = -1; // end of file private static int buffer; // one character buffer private static int N; // number of bits left in buffer // static initializer static { fillBuffer(); } // singleton pattern - can't instantiate private BinaryStdIn() { } private static void fillBuffer() { try { buffer = in.read(); N = 8; } catch (IOException e) { System.out.println("EOF"); buffer = EOF; N = -1; } } /** * Returns true if standard input is empty. * @return true if and only if standard input is empty */ public static boolean isEmpty() { return buffer == EOF; } /** * Read the next bit of data from standard input and return as a boolean. * @return the next bit of data from standard input as a <tt>boolean</tt> * @throws RuntimeException if standard input is empty */ public static boolean readBoolean() { if (isEmpty()) throw new RuntimeException("Reading from empty input stream"); N--; boolean bit = ((buffer >> N) & 1) == 1; if (N == 0) fillBuffer(); return bit; } /** * Read the next 8 bits from standard input and return as an 8-bit char. * @return the next 8 bits of data from standard input as a <tt>char</tt> * @throws RuntimeException if there are fewer than 8 bits available on standard input */ public static char readChar() { if (isEmpty()) throw new RuntimeException("Reading from empty input stream"); // special case when aligned byte if (N == 8) { int x = buffer; fillBuffer(); return (char) (x & 0xff); } // combine last N bits of current buffer with first 8-N bits of new buffer int x = buffer; x <<= (8-N); int oldN = N; fillBuffer(); if (isEmpty()) throw new RuntimeException("Reading from empty input stream"); N = oldN; x |= (buffer >>> N); return (char) (x & 0xff); // the above code doesn't quite work for the last character if N = 8 // because buffer will be -1 } /** * Read the next r bits from standard input and return as an r-bit character. * @param r number of bits to read. * @return the next r bits of data from standard input as a <tt>char</tt> * @throws RuntimeException if there are fewer than r bits available on standard input */ public static char readChar(int r) { if (r < 1 || r > 16) throw new RuntimeException("Illegal value of r = " + r); // optimize r = 8 case if (r == 8) return readChar(); char x = 0; for (int i = 0; i < r; i++) { x <<= 1; boolean bit = readBoolean(); if (bit) x |= 1; } return x; } /** * Read the remaining bytes of data from standard input and return as a string. * @return the remaining bytes of data from standard input as a <tt>String</tt> * @throws RuntimeException if standard input is empty or if the number of bits * available on standard input is not a multiple of 8 (byte-aligned) */ public static String readString() { if (isEmpty()) throw new RuntimeException("Reading from empty input stream"); StringBuilder sb = new StringBuilder(); while (!isEmpty()) { char c = readChar(); sb.append(c); } return sb.toString(); } /** * Read the next 16 bits from standard input and return as a 16-bit short. * @return the next 16 bits of data from standard input as a <tt>short</tt> * @throws RuntimeException if there are fewer than 16 bits available on standard input */ public static short readShort() { short x = 0; for (int i = 0; i < 2; i++) { char c = readChar(); x <<= 8; x |= c; } return x; } /** * Read the next 32 bits from standard input and return as a 32-bit int. * @return the next 32 bits of data from standard input as a <tt>int</tt> * @throws RuntimeException if there are fewer than 32 bits available on standard input */ public static int readInt() { int x = 0; for (int i = 0; i < 4; i++) { char c = readChar(); x <<= 8; x |= c; } return x; } /** * Read the next r bits from standard input and return as an r-bit int. * @param r number of bits to read. * @return the next r bits of data from standard input as a <tt>int</tt> * @throws RuntimeException if there are fewer than r bits available on standard input */ public static int readInt(int r) { if (r < 1 || r > 32) throw new RuntimeException("Illegal value of r = " + r); // optimize r = 32 case if (r == 32) return readInt(); int x = 0; for (int i = 0; i < r; i++) { x <<= 1; boolean bit = readBoolean(); if (bit) x |= 1; } return x; } /** * Read the next 64 bits from standard input and return as a 64-bit long. * @return the next 64 bits of data from standard input as a <tt>long</tt> * @throws RuntimeException if there are fewer than 64 bits available on standard input */ public static long readLong() { long x = 0; for (int i = 0; i < 8; i++) { char c = readChar(); x <<= 8; x |= c; } return x; } /** * Read the next 64 bits from standard input and return as a 64-bit double. * @return the next 64 bits of data from standard input as a <tt>double</tt> * @throws RuntimeException if there are fewer than 64 bits available on standard input */ public static double readDouble() { return Double.longBitsToDouble(readLong()); } /** * Read the next 32 bits from standard input and return as a 32-bit float. * @return the next 32 bits of data from standard input as a <tt>float</tt> * @throws RuntimeException if there are fewer than 32 bits available on standard input */ public static float readFloat() { return Float.intBitsToFloat(readInt()); } /** * Read the next 8 bits from standard input and return as an 8-bit byte. * @return the next 8 bits of data from standard input as a <tt>byte</tt> * @throws RuntimeException if there are fewer than 8 bits available on standard input */ public static byte readByte() { char c = readChar(); byte x = (byte) (c & 0xff); return x; } /** * Test client. Reads in a binary input file from standard input and writes * it to standard output. */ public static void main(String[] args) { // read one 8-bit char at a time while (!BinaryStdIn.isEmpty()) { char c = BinaryStdIn.readChar(); BinaryStdOut.write(c); } BinaryStdOut.flush(); } }