JRE 8 rt.jar is the JAR file for JRE 8 RT (Runtime) libraries. JRE (Java Runtime) 8 is the runtime environment included in JDK 8. JRE 8 rt.jar libraries are divided into 6 packages:

com.* - Internal Oracle and Sun Microsystems libraries
java.* - Standard Java API libraries.
javax.* - Extended Java API libraries.
jdk.* -  JDK supporting libraries.
org.* - Third party libraries.
sun.* - Old libraries developed by Sun Microsystems.

JAR File Information:

Directory of C:\fyicenter\jdk-1.8.0_191\jre\lib
      63,596,151 rt.jar

Here is the list of Java classes of the javax.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ javax/imageio/stream/ImageOutputStreamImpl.java

/*
 * Copyright (c) 2000, 2007, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package javax.imageio.stream;

import java.io.IOException;
import java.io.UTFDataFormatException;
import java.nio.ByteOrder;

/**
 * An abstract class implementing the <code>ImageOutputStream</code> interface.
 * This class is designed to reduce the number of methods that must
 * be implemented by subclasses.
 *
 */
public abstract class ImageOutputStreamImpl
    extends ImageInputStreamImpl
    implements ImageOutputStream {

    /**
     * Constructs an <code>ImageOutputStreamImpl</code>.
     */
    public ImageOutputStreamImpl() {
    }

    public abstract void write(int b) throws IOException;

    public void write(byte b[]) throws IOException {
        write(b, 0, b.length);
    }

    public abstract void write(byte b[], int off, int len) throws IOException;

    public void writeBoolean(boolean v) throws IOException {
        write(v ? 1 : 0);
    }

    public void writeByte(int v) throws IOException {
        write(v);
    }

    public void writeShort(int v) throws IOException {
        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            byteBuf[0] = (byte)(v >>> 8);
            byteBuf[1] = (byte)(v >>> 0);
        } else {
            byteBuf[0] = (byte)(v >>> 0);
            byteBuf[1] = (byte)(v >>> 8);
        }
        write(byteBuf, 0, 2);
    }

    public void writeChar(int v) throws IOException {
        writeShort(v);
    }

    public void writeInt(int v) throws IOException {
        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            byteBuf[0] = (byte)(v >>> 24);
            byteBuf[1] = (byte)(v >>> 16);
            byteBuf[2] = (byte)(v >>>  8);
            byteBuf[3] = (byte)(v >>>  0);
        } else {
            byteBuf[0] = (byte)(v >>>  0);
            byteBuf[1] = (byte)(v >>>  8);
            byteBuf[2] = (byte)(v >>> 16);
            byteBuf[3] = (byte)(v >>> 24);
        }
        write(byteBuf, 0, 4);
    }

    public void writeLong(long v) throws IOException {
        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            byteBuf[0] = (byte)(v >>> 56);
            byteBuf[1] = (byte)(v >>> 48);
            byteBuf[2] = (byte)(v >>> 40);
            byteBuf[3] = (byte)(v >>> 32);
            byteBuf[4] = (byte)(v >>> 24);
            byteBuf[5] = (byte)(v >>> 16);
            byteBuf[6] = (byte)(v >>>  8);
            byteBuf[7] = (byte)(v >>>  0);
        } else {
            byteBuf[0] = (byte)(v >>>  0);
            byteBuf[1] = (byte)(v >>>  8);
            byteBuf[2] = (byte)(v >>> 16);
            byteBuf[3] = (byte)(v >>> 24);
            byteBuf[4] = (byte)(v >>> 32);
            byteBuf[5] = (byte)(v >>> 40);
            byteBuf[6] = (byte)(v >>> 48);
            byteBuf[7] = (byte)(v >>> 56);
        }
        // REMIND: Once 6277756 is fixed, we should do a bulk write of all 8
        // bytes here as we do in writeShort() and writeInt() for even better
        // performance.  For now, two bulk writes of 4 bytes each is still
        // faster than 8 individual write() calls (see 6347575 for details).
        write(byteBuf, 0, 4);
        write(byteBuf, 4, 4);
    }

    public void writeFloat(float v) throws IOException {
        writeInt(Float.floatToIntBits(v));
    }

    public void writeDouble(double v) throws IOException {
        writeLong(Double.doubleToLongBits(v));
    }

    public void writeBytes(String s) throws IOException {
        int len = s.length();
        for (int i = 0 ; i < len ; i++) {
            write((byte)s.charAt(i));
        }
    }

    public void writeChars(String s) throws IOException {
        int len = s.length();

        byte[] b = new byte[len*2];
        int boff = 0;
        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            for (int i = 0; i < len ; i++) {
                int v = s.charAt(i);
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 0);
            }
        } else {
            for (int i = 0; i < len ; i++) {
                int v = s.charAt(i);
                b[boff++] = (byte)(v >>> 0);
                b[boff++] = (byte)(v >>> 8);
            }
        }

        write(b, 0, len*2);
    }

    public void writeUTF(String s) throws IOException {
        int strlen = s.length();
        int utflen = 0;
        char[] charr = new char[strlen];
        int c, boff = 0;

        s.getChars(0, strlen, charr, 0);

        for (int i = 0; i < strlen; i++) {
            c = charr[i];
            if ((c >= 0x0001) && (c <= 0x007F)) {
                utflen++;
            } else if (c > 0x07FF) {
                utflen += 3;
            } else {
                utflen += 2;
            }
        }

        if (utflen > 65535) {
            throw new UTFDataFormatException("utflen > 65536!");
        }

        byte[] b = new byte[utflen+2];
        b[boff++] = (byte) ((utflen >>> 8) & 0xFF);
        b[boff++] = (byte) ((utflen >>> 0) & 0xFF);
        for (int i = 0; i < strlen; i++) {
            c = charr[i];
            if ((c >= 0x0001) && (c <= 0x007F)) {
                b[boff++] = (byte) c;
            } else if (c > 0x07FF) {
                b[boff++] = (byte) (0xE0 | ((c >> 12) & 0x0F));
                b[boff++] = (byte) (0x80 | ((c >>  6) & 0x3F));
                b[boff++] = (byte) (0x80 | ((c >>  0) & 0x3F));
            } else {
                b[boff++] = (byte) (0xC0 | ((c >>  6) & 0x1F));
                b[boff++] = (byte) (0x80 | ((c >>  0) & 0x3F));
            }
        }
        write(b, 0, utflen + 2);
    }

    public void writeShorts(short[] s, int off, int len) throws IOException {
        // Fix 4430357 - if off + len < 0, overflow occurred
        if (off < 0 || len < 0 || off + len > s.length || off + len < 0) {
            throw new IndexOutOfBoundsException
                ("off < 0 || len < 0 || off + len > s.length!");
        }

        byte[] b = new byte[len*2];
        int boff = 0;
        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            for (int i = 0; i < len; i++) {
                short v = s[off + i];
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 0);
            }
        } else {
            for (int i = 0; i < len; i++) {
                short v = s[off + i];
                b[boff++] = (byte)(v >>> 0);
                b[boff++] = (byte)(v >>> 8);
            }
        }

        write(b, 0, len*2);
    }

    public void writeChars(char[] c, int off, int len) throws IOException {
        // Fix 4430357 - if off + len < 0, overflow occurred
        if (off < 0 || len < 0 || off + len > c.length || off + len < 0) {
            throw new IndexOutOfBoundsException
                ("off < 0 || len < 0 || off + len > c.length!");
        }

        byte[] b = new byte[len*2];
        int boff = 0;
        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            for (int i = 0; i < len; i++) {
                char v = c[off + i];
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 0);
            }
        } else {
            for (int i = 0; i < len; i++) {
                char v = c[off + i];
                b[boff++] = (byte)(v >>> 0);
                b[boff++] = (byte)(v >>> 8);
            }
        }

        write(b, 0, len*2);
    }

    public void writeInts(int[] i, int off, int len) throws IOException {
        // Fix 4430357 - if off + len < 0, overflow occurred
        if (off < 0 || len < 0 || off + len > i.length || off + len < 0) {
            throw new IndexOutOfBoundsException
                ("off < 0 || len < 0 || off + len > i.length!");
        }

        byte[] b = new byte[len*4];
        int boff = 0;
        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            for (int j = 0; j < len; j++) {
                int v = i[off + j];
                b[boff++] = (byte)(v >>> 24);
                b[boff++] = (byte)(v >>> 16);
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 0);
            }
        } else {
            for (int j = 0; j < len; j++) {
                int v = i[off + j];
                b[boff++] = (byte)(v >>> 0);
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 16);
                b[boff++] = (byte)(v >>> 24);
            }
        }

        write(b, 0, len*4);
    }

    public void writeLongs(long[] l, int off, int len) throws IOException {
        // Fix 4430357 - if off + len < 0, overflow occurred
        if (off < 0 || len < 0 || off + len > l.length || off + len < 0) {
            throw new IndexOutOfBoundsException
                ("off < 0 || len < 0 || off + len > l.length!");
        }

        byte[] b = new byte[len*8];
        int boff = 0;
        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            for (int i = 0; i < len; i++) {
                long v = l[off + i];
                b[boff++] = (byte)(v >>> 56);
                b[boff++] = (byte)(v >>> 48);
                b[boff++] = (byte)(v >>> 40);
                b[boff++] = (byte)(v >>> 32);
                b[boff++] = (byte)(v >>> 24);
                b[boff++] = (byte)(v >>> 16);
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 0);
            }
        } else {
            for (int i = 0; i < len; i++) {
                long v = l[off + i];
                b[boff++] = (byte)(v >>> 0);
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 16);
                b[boff++] = (byte)(v >>> 24);
                b[boff++] = (byte)(v >>> 32);
                b[boff++] = (byte)(v >>> 40);
                b[boff++] = (byte)(v >>> 48);
                b[boff++] = (byte)(v >>> 56);
            }
        }

        write(b, 0, len*8);
    }

    public void writeFloats(float[] f, int off, int len) throws IOException {
        // Fix 4430357 - if off + len < 0, overflow occurred
        if (off < 0 || len < 0 || off + len > f.length || off + len < 0) {
            throw new IndexOutOfBoundsException
                ("off < 0 || len < 0 || off + len > f.length!");
        }

        byte[] b = new byte[len*4];
        int boff = 0;
        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            for (int i = 0; i < len; i++) {
                int v = Float.floatToIntBits(f[off + i]);
                b[boff++] = (byte)(v >>> 24);
                b[boff++] = (byte)(v >>> 16);
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 0);
            }
        } else {
            for (int i = 0; i < len; i++) {
                int v = Float.floatToIntBits(f[off + i]);
                b[boff++] = (byte)(v >>> 0);
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 16);
                b[boff++] = (byte)(v >>> 24);
            }
        }

        write(b, 0, len*4);
    }

    public void writeDoubles(double[] d, int off, int len) throws IOException {
        // Fix 4430357 - if off + len < 0, overflow occurred
        if (off < 0 || len < 0 || off + len > d.length || off + len < 0) {
            throw new IndexOutOfBoundsException
                ("off < 0 || len < 0 || off + len > d.length!");
        }

        byte[] b = new byte[len*8];
        int boff = 0;
        if (byteOrder == ByteOrder.BIG_ENDIAN) {
            for (int i = 0; i < len; i++) {
                long v = Double.doubleToLongBits(d[off + i]);
                b[boff++] = (byte)(v >>> 56);
                b[boff++] = (byte)(v >>> 48);
                b[boff++] = (byte)(v >>> 40);
                b[boff++] = (byte)(v >>> 32);
                b[boff++] = (byte)(v >>> 24);
                b[boff++] = (byte)(v >>> 16);
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 0);
            }
        } else {
            for (int i = 0; i < len; i++) {
                long v = Double.doubleToLongBits(d[off + i]);
                b[boff++] = (byte)(v >>> 0);
                b[boff++] = (byte)(v >>> 8);
                b[boff++] = (byte)(v >>> 16);
                b[boff++] = (byte)(v >>> 24);
                b[boff++] = (byte)(v >>> 32);
                b[boff++] = (byte)(v >>> 40);
                b[boff++] = (byte)(v >>> 48);
                b[boff++] = (byte)(v >>> 56);
            }
        }

        write(b, 0, len*8);
    }

    public void writeBit(int bit) throws IOException {
        writeBits((1L & bit), 1);
    }

    public void writeBits(long bits, int numBits) throws IOException {
        checkClosed();

        if (numBits < 0 || numBits > 64) {
            throw new IllegalArgumentException("Bad value for numBits!");
        }
        if (numBits == 0) {
            return;
        }

        // Prologue: deal with pre-existing bits

        // Bug 4499158, 4507868 - if we're at the beginning of the stream
        // and the bit offset is 0, there can't be any pre-existing bits
        if ((getStreamPosition() > 0) || (bitOffset > 0)) {
            int offset = bitOffset;  // read() will reset bitOffset
            int partialByte = read();
            if (partialByte != -1) {
                seek(getStreamPosition() - 1);
            } else {
                partialByte = 0;
            }

            if (numBits + offset < 8) {
                // Notch out the partial byte and drop in the new bits
                int shift = 8 - (offset+numBits);
                int mask = -1 >>> (32 - numBits);
                partialByte &= ~(mask << shift);  // Clear out old bits
                partialByte |= ((bits & mask) << shift); // Or in new ones
                write(partialByte);
                seek(getStreamPosition() - 1);
                bitOffset = offset + numBits;
                numBits = 0;  // Signal that we are done
            } else {
                // Fill out the partial byte and reduce numBits
                int num = 8 - offset;
                int mask = -1 >>> (32 - num);
                partialByte &= ~mask;  // Clear out bits
                partialByte |= ((bits >> (numBits - num)) & mask);
                // Note that bitOffset is already 0, so there is no risk
                // of this advancing to the next byte
                write(partialByte);
                numBits -= num;
            }
        }

        // Now write any whole bytes
        if (numBits > 7) {
            int extra = numBits % 8;
            for (int numBytes = numBits / 8; numBytes > 0; numBytes--) {
                int shift = (numBytes-1)*8+extra;
                int value = (int) ((shift == 0)
                                   ? bits & 0xFF
                                   : (bits>>shift) & 0xFF);
                write(value);
            }
            numBits = extra;
        }

        // Epilogue: write out remaining partial byte, if any
        // Note that we may be at EOF, in which case we pad with 0,
        // or not, in which case we must preserve the existing bits
        if (numBits != 0) {
            // If we are not at the end of the file, read the current byte
            // If we are at the end of the file, initialize our byte to 0.
            int partialByte = 0;
            partialByte = read();
            if (partialByte != -1) {
                seek(getStreamPosition() - 1);
            }
            // Fix 4494976: writeBit(int) does not pad the remainder
            // of the current byte with 0s
            else { // EOF
                partialByte = 0;
            }

            int shift = 8 - numBits;
            int mask = -1 >>> (32 - numBits);
            partialByte &= ~(mask << shift);
            partialByte |= (bits & mask) << shift;
            // bitOffset is always already 0 when we get here.
            write(partialByte);
            seek(getStreamPosition() - 1);
            bitOffset = numBits;
        }
    }

    /**
     * If the bit offset is non-zero, forces the remaining bits
     * in the current byte to 0 and advances the stream position
     * by one.  This method should be called by subclasses at the
     * beginning of the <code>write(int)</code> and
     * <code>write(byte[], int, int)</code> methods.
     *
     * @exception IOException if an I/O error occurs.
     */
    protected final void flushBits() throws IOException {
        checkClosed();
        if (bitOffset != 0) {
            int offset = bitOffset;
            int partialByte = read(); // Sets bitOffset to 0
            if (partialByte < 0) {
                // Fix 4465683: When bitOffset is set
                // to something non-zero beyond EOF,
                // we should set that whole byte to
                // zero and write it to stream.
                partialByte = 0;
                bitOffset = 0;
            }
            else {
                seek(getStreamPosition() - 1);
                partialByte &= -1 << (8 - offset);
            }
            write(partialByte);
        }
    }

}

⏎ javax/imageio/stream/ImageOutputStreamImpl.java

Or download all of them as a single archive file:

File name: jre-rt-javax-1.8.0_191-src.zip
File size: 5381005 bytes
Release date: 2018-10-28
Download 

⇒ JRE 8 rt.jar - org.* Package Source Code

⇐ JRE 8 rt.jar - java.* Package Source Code

⇑ Download and Use JDK 8

⇑⇑ FAQ for JDK (Java Development Kit)