Java File I/O Streams Flashcards

Questions and Answers

What is the File I/O API?

java.io.File

What does URI mean?

Uniform Resource Identifier

The File class performs Data Input or Output processes.

False

What does the File class do?

provides information (metadata) about a file or directory. Signup and view all the answers

What does a Stream represent?

A sequence of data. Signup and view all the answers

What is an input stream?

reads data from a source (does not have to be a file). Signup and view all the answers

What is an output stream?

writes data to a source (does not have to be a file). Signup and view all the answers

What are the 5 types of streams in I/O?

Byte stream, Character stream, Buffered Streams, Object Streams, Line Oriented I/O. Signup and view all the answers

What is a Byte Stream?

A low level API that writes data in bytes. Signup and view all the answers

What is a Character Stream?

A higher level API that automatically changes data in a file to character (text) data. Signup and view all the answers

What is a Buffered Stream?

Used to increase performance by avoiding OS level I/O operations for each character that is read or written. Signup and view all the answers

What is an Object Stream?

Reads and writes Java objects to a file. Objects must implement java.io.Serializable. Signup and view all the answers

What is Sequential File Access?

Cannot insert or change data in the middle of file without re-writing the whole file. Signup and view all the answers

What is Random File Access?

Data is viewed in an array of bytes that can be accessed at a particular position. Signup and view all the answers

Which class allows for Random File Access?

java.io.RandomAccessFile Signup and view all the answers

What is a binary file?

A computer file that is not a text file; it may contain data encoded in binary form. Signup and view all the answers

What is Serialization?

Allows a program to write whole objects out to streams and read them back again. Signup and view all the answers

What does the acronym I/O stand for?

Input/Output Signup and view all the answers

Which APIs does Character Stream use for I/O?

java.io.FileReader; java.io.FileWriter; Signup and view all the answers

Which APIs does Byte Stream use for I/O?

java.io.FileInputStream; java.io.FileOutputStream; Signup and view all the answers

How does Java view each file?

As a sequential stream of bytes. Signup and view all the answers

Explain a Character Stream.

Output and input data as a sequence of characters with every character being 2 bytes. Signup and view all the answers

Explain a Byte-Based Stream.

Output and input data in its binary format. Signup and view all the answers

What are the 3 stream objects created when Java opens a file?

System.in, System.out, System.err Signup and view all the answers

What are the Buffered Stream APIs used to read character streams?

java.io.BufferedReader; java.io.BufferedWriter; Signup and view all the answers

What are the Buffered Stream APIs used to read byte streams?

java.io.BufferedInputStream; java.io.BufferedOutputStream; Signup and view all the answers

Explain the 'flush' method.

The flush method clears the buffer. It's only available on buffered output streams. Signup and view all the answers

What are the 3 standard streams supported by the Java Platform?

System.in, System.out, System.err Signup and view all the answers

The console provides a byte stream.

False Signup and view all the answers

What type of stream do the 3 standard streams provide?

Byte. Signup and view all the answers

How do you invoke the Console?

System.console() Signup and view all the answers

If the console is not available what is the return value?

null Signup and view all the answers

What API is used with Console?

Java.io.Console; Signup and view all the answers

Which Console method supports secure password entry?

readPassword() Signup and view all the answers

Which APIs are used to implement Data Streams?

Java.io.DataInputStream; Java.io.DataOutputStream; Signup and view all the answers

Study Notes

File I/O API Overview

The File I/O API is represented by java.io.File, which manages file operations.
URI stands for Uniform Resource Identifier; an example is file c://c:/data.txt.

File Class Functionality

The File class does not handle data input or output processes.
Provides metadata about files and directories.

Streams in Java

Streams represent sequences of data.
Input streams read data from various sources, not limited to files.
Output streams write data to various sources, also not limited to files.

Types of Streams

Types of streams in Java I/O include:
- Byte stream
- Character stream
- Buffered streams
- Object streams
- Line-oriented I/O

Stream Characteristics

Byte streams offer a low-level API for handling data in bytes.
Character streams provide a higher-level API that converts data to text format automatically.
Buffered streams enhance performance by minimizing direct OS I/O operations, utilizing internal buffers.
Object streams read and write Java objects to files; objects must implement java.io.Serializable.

File Access Methods

Sequential file access means data cannot be modified in the middle without rewriting the entire file.
Random file access allows direct access to data at any position in the file.

Random Access File Class

The java.io.RandomAccessFile class enables random file access, allowing binary read and write operations.

File Types and Serialization

Binary files store data in binary format and can be distinguished from text files.
Serialization facilitates writing entire objects to streams and retrieving them later.

Input/Output Concepts

The acronym I/O stands for Input/Output.
Character streams utilize java.io.FileReader and java.io.FileWriter for I/O operations.
Byte streams rely on java.io.FileInputStream and java.io.FileOutputStream.

Java File Representation

Java treats each file as a sequential stream of bytes.
Character streams process data as sequences of characters, with each character representing 2 bytes.
Byte streams handle data in binary format, where a char is 2 bytes, int is 4 bytes, and double is 8 bytes.

Stream Objects and Buffered Streams

Java creates three standard stream objects upon opening a file: System.in, System.out, and System.err.
Buffered stream APIs for character streams include java.io.BufferedReader and java.io.BufferedWriter.
Buffered stream APIs for byte streams consist of java.io.BufferedInputStream and java.io.BufferedOutputStream.

Buffer Flushing and Console Management

The flush method clears the buffer in buffered output streams.
Standard streams supported by Java include System.in, System.out, and System.err.
The console provides a true character stream, while the standard streams provide byte streams.
The console is invoked using System.console(), returning null if unavailable.

Console API and Password Handling

The Console API is represented by java.io.Console.
The readPassword() method in the Console class supports secure password entry.

Data Streams

Data streams are implemented using java.io.DataInputStream and java.io.DataOutputStream.
Data Input Streams support various data types, enabling type-specific read and write operations.

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Description

Test your knowledge on Java's File I/O API with these flashcards. Each card highlights key concepts and terminology essential for understanding file operations in Java. Ideal for students and developers looking to strengthen their Java programming skills.