Java SE NIO

This exam covers non-blocking IO introduced since Java 1.4 in java.nio.* packages.
Topics about regular expressions and character sets are not covered.

Resources

Based on the "Java NIO"

book by Ron Hitchens (published by O'Reilly), this exam covers Chapters 1 - 4:

Chapter 1. INTRODUCTION
1.1 I/O Versus CPU Time
1.2 No Longer CPU Bound
1.3 Getting to the Good Stuff
1.4 I/O Concepts
1.5 Summary
Chapter 2. BUFFERS
2.1 Buffer Basics
2.2 Creating Buffers
2.3 Duplicating Buffers
2.4 Byte Buffers
2.5 Summary
Chapter 3. CHANNELS
3.1 Channel Basics
3.2 Scatter/Gather
3.3 File Channels
3.4 Memory-Mapped Files
3.5 Socket Channels
3.6 Pipes
3.7 The Channels Utility Class
3.8 Summary
Chapter 4. SELECTORS
4.1 Selector Basics
4.2 Using Selection Keys
4.3 Using Selectors
4.4 Asynchronous Closability
4.5 Selection Scaling
4.6 Summary

See the Java NIO JavaDoc

for more information.

	Released	Beta	Frozen
NIO basic concepts 2 questions Demonstrate the understanding of basic NIO ideology Explain the differences in approaches between NIO and classical IO Enumerate the main usages of NIO (like non-blocking IO)	5	9	9	Add a question Beta questions
Buffers 3 questions Show ability to manipulate `ByteBuffer` (specific functions for HeapByteBuffer, DirectByteBuffer and MappedByteBuffer are not covered) Be able to write code that uses buffers: Create `ByteBuffer` Add data to buffer Remove data from buffer Be able to use each buffer's parameter: position limit capacity Explain why `0 <= mark <= position <= limit <= capacity` is true in all cases	5	47	9	Add a question Beta questions
Channels 4 questions Display understanding of channels Explain the purpose of using channels Describe the purpose of basic channel interfaces and classes: Channel ReadableByteChannel WritableByteChannel ByteChannel FileChannel SocketChannel DatagramChannel Write code to construct and use `FileChannel` and `SocketChannel`: Create channels: RandomAccessFile.getChannel() Socket.getChannel() Write data to channel: WritableByteChannel.write(ByteBuffer src); Note that `write` operation might not write all the buffer during one writing loop. Read data from channel: ReadableByteChannel.read(ByteBuffer dst); Note that `read` operation might not fill all the buffer during one reading loop. Close channel Handle channels' exceptions	8	15	7	Add a question Beta questions
Selectors 5 questions This category covers questions about selectors - an approach to handle large number of reading/writing channels simultaneously. Give usage description for basic classes: Selector Opening selector Selecting keys: Use `Selector.select()` to get ready selection keys Explain difference between `Selector.select()` and `Selector.select(int)` Be able to stop key selection process using `wakeUp()` Closing selector SelectableChannel Bind channel to `Selector` in different modes: SelectionKey.OP_ACCEPT SelectionKey.OP_CONNECT SelectionKey.OP_READ SelectionKey.OP_WRITE Be able to use the appropriate mode in a given situation SelectionKey Explain what `SelectionKey` is used for Use `SelectionKey.attach(Object)` and `SelectionKey.attachment()` to manipulate SelectionKey's specific data Be able to write code that uses them Explain the difference `SelectableChannel`'s blocking and non-blocking modes. Be able to choose the most appropriate mode in a given situation. Explain why selectors can be scaled (no need to use a thread per connection)	8	7	4	Add a question Beta questions