API Contents - SCJP Sun Certified Programmer for Java Platform SE6 - page 284

Table 4.1 lists the low-level and high-level streams from the java.io package.

TABLE 4.1 The Low-Level and High-Level Streams in the java.io Package

High-level Streams

Low-level Streams

FileInputStream BufferedReader BufferedInputStream

FileReader

FileOutputStream BufferedWriter BufferedOutputStream

FileWriter

ByteArrayInputStream CharArrayWriter DataInputStream ObjectInputStream

StringReader StringWriter PipedInputStream OutputStreamWriter

InputStream OutputStream PipedOutputStream InputStreamReader

PushbackInput
Stream

LineNumberReader

PushbackReader

PushbackReader

Determining Low-level vs. High-level Streams

If you ever need to determine whether a java.io stream is a high-level or low-level
stream, just look at the constructors of the class. If the constructors take in an
existing stream object, then it is a high-level stream; otherwise, it is a low-level stream.

For example, the DataInputStream class has only one constructor:

public DataInputStream(InputStream is)

You cannot instantiate a DataInputStream unless you already have an existing stream to
pass in to the constructor. Therefore, DataInputStream must be a high-level stream.

Compare DataInputStream to FileInputStream , which has three constructors:

public FileInputStream(File file)
public FileInputStream(FileDescriptor fdObj)
public FileInputStream(String name)

Each constructor takes in some variation of a fi le, which is the source of the data and not
another stream class. Therefore, FileInputStream is a low-level stream.