Intro to I/O in Java

Terms

stream

A source for input or a destination for output.

whitespace

Refers to the space, tab, and newline characters.

delimiter

Any character that is used to separate individual tokens.

token

A portion of a string defined by a set of delimiters.

absolute pathname

The directory path to a file location that begins with the root of the directory in which the file is located.

relative pathname

The directory path to a file location that begins with the current working directory.

checked exception

An exception that must be handled or thrown in a program. I/O errors are checked exceptions.

unchecked exception

An exception that may be ignored in a program. Descendents of the RuntimeException are the only unchecked exceptions in java.

Classes you should know

Scanner

Specifically, its use related to input and tokenizing a String.

File

The class to specify file names for both input and output.

PrintWriter

The class used to print to files.

StringTokenizer

A class that can be used to tokenize String objects.

Today's notes

Review solution to Wednesday lab

I/O Basics

• Streams
• Java classes that we have used
  • Scanner - System.in
  • PrintStream - System.out
• File processing - new classes
  • File
  • PrintWriter
  • Absolute vs relative path names
  • IO.java
• Exceptions that occur with file processing
  • Checked vs unchecked exceptions
  • Java treats RuntimeException descendents as unchecked

Scanner uses

• Input from the keyboard (System.in)
• Input from File objects
  • Be aware that Scanner ignores newline characters.
• Manipulating String object data

String tokenizer - an introduction

More information about the File class