Java IO (Input/Output) Tutorials

Java IO is a collection of APIs targeted at reading and writing data from various sources to several targets. For example, we can read data from a file or over a network, write to a file or write a response back over the network.

This page categorizes the various IO-related common tasks into a logical grouping so you can refer to various solutions of a particular problem and choose what fits best to your requirements.

1. Working with Files

• Creating a New File
• Reading a File to String
• Reading a File to Byte[]
• Reading a File Line by Line
• Reading a File from Classpath
• Reading a File from Resources Directory
• Writing to a File
• Appending to a File
• Reading and Writing UTF-8 Data
• Rename or Move a File or Directory
• Copying a File
• Deleting a File or Directory
• Getting Size of File or Directory
• Reading a Large File Efficiently
• Reading a File at a Given Line Number
• Reading a CSV File into an Array
• Read a File into an ArrayList
• Count Number of Lines
• Writing byte[] to a File
• Delete the Contents of a File
• Check If a File or Directory Exists
• Getting File Creation Timestamp
• Working with Symbolic Links
• Making a File Read Only
• How to Find a File in Directory

2. Working with Temporary Files

• Create Temporary File
• Write Temporary File
• Delete Temporary File

3. Working with Directories

• Creating New Directories
• Check if a Directory is Empty
• Listing All Files in a Directory
• Get Current Working Directory
• Copying a Directory
• Delete a Directory Recursively
• Filtering Files with FileFilter
• Finding Files Matching Pattern with FilenameFilter

4. Conversions

• Convert String to InputStream
• Convert InputStream to String
• Convert InputStream to Reader and Vice Versa
• Convert InputStream to OutputStream
• Convert OutputStream to InputStream
• Reader to String and Vice Versa
• Reader to Byte Array and Vice Versa
• Write a Reader to File and Vice Versa

5. Java Standard IO

• BufferedReader
• BufferedWriter
• StringReader
• FileReader
• FileWriter
• InputStreamReader
• LineNumberReader

6. Java New IO

• Introduction to the Java NIO
• Standard IO vs New IO
• NIO Paths
• Getting Filesystem Paths
• NIO Buffers
• NIO Channels
• Vectored IO
• NIO MappedByteBuffer
• Reading a File with Channels and Buffers

7. Advance Topics

• How does Java IO Works Internally?
• Reading User Input from Console
• Read typesafe input using Scanner class
• Encrypting and Decrypting Files
• Reading and Writing Properties Files
• Java Create Password Protected Zip File
• Java Unzip File with Subdirectories

Source Code on Github