Circular Buffers

The com.Ostermiller.util package contains three flavors of circular buffer. Each type is presented here along with a simple example.

Circular Object Buffer

Implements the circular buffer producer/consumer model for Objects.

Example

// Create the buffer.
CircularObjectBuffer cob = new CircularObjectBuffer();

// Fill the buffer.
cob.write("Hello World!\n");

// Empty the buffer.
System.out.print((String)(cob.read()));

This example only works because "Hello World" is one object. If you try to write more objects than the size of the buffer, the buffer will block until space is available. In this single thread example, that will appear to cause a program hang. You can get around this by making the buffer infinite size or emptying the buffer in another thread.

Circular Character Buffer

Implements the circular buffer producer/consumer model for characters. Filling and emptying the buffer is done with standard Java Readers and Writers.

Using this class is a simpler alternative to using a PipedReader and a PipedWriter. PipedReaders and PipedWriters don't support the mark operation, don't allow you to control buffer sizes that they use, and have a more complicated API that requires a instantiating two classes and connecting them.

Example

// Create the buffer.
CircularCharBuffer ccb = new CircularCharBuffer();

// Fill the buffer.
ccb.getWriter().write("Hello World!\n");
ccb.getWriter().close();

// Empty the buffer.
int c;
while ((c = ccb.getReader().read()) != -1){
    System.out.print((char)c);
}

This example only works because "Hello World" is short. If you try to write more data than the size of the buffer, the buffer will block until space is available. In this single thread example, that will appear to cause a program hang. You can get around this by making the buffer infinite size or emptying the buffer in another thread.

Circular Byte Buffer

Implements the circular buffer producer/consumer model for bytes. Filling and emptying the buffer is done with standard Java InputStreams and OutputStreams.

Using this class is a simpler alternative to using a PipedInputStream and a PipedOutputStream. PipedInputStreams and PipedOutputStreams don't support the mark operation, don't allow you to control buffer sizes that they use, and have a more complicated API that requires a instantiating two classes and connecting them.

Example

// Create the buffer.
CircularByteBuffer cbb = new CircularByteBuffer();

// Fill the buffer.
cbb.getOutputStream().write(
    new byte[]{
        'H','e','l','l','o',' ',
        'W','o','r','l','d','!','\n'
    }
);
cbb.getOutputStream().close();

// Empty the buffer.
int c;
while ((c = cbb.getInputStream().read()) != -1){
    System.out.print((char)c);
}

This example only works because "Hello World" is short. If you try to write more data than the size of the buffer, the buffer will block until space is available. In this single thread example, that will appear to cause a program hang. You can get around this by making the buffer infinite size or emptying the buffer in another thread.