Apache Commons IO - IOUtils Class

---

---

Overview

IOUtils class provide utility methods for reading, writing and copying files. The methods work with InputStream, OutputStream, Reader and Writer.

Class Declaration

Following is the declaration for org.apache.commons.io.IOUtils Class −

public class IOUtils
   extends Object

Features of IOUtils

The features of IOUtils are given below −

• Provides static utility methods for input/output operations.

• toXXX() − reads data from a stream.

• write() − write data to a stream.

• copy() − copy all data to a stream to another stream.

• contentEquals − compare the contents of two streams.

Here is the input file we need to parse −

input.txt

Welcome to TutorialsPoint. 
Simply Easy Learning.

Example - Convert Stream to String using IOUtils

CommonsIoTester.java

package com.tutorialspoint;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.io.IOUtils;

public class CommonsIoTester {
   public static void main(String[] args) throws IOException {
      try(InputStream in = new FileInputStream("input.txt")) {
         String data = IOUtils.toString( in , "UTF-8");
		 System.out.println(data);
      }
   }
}

Output

It will print the following result −

Welcome to TutorialsPoint. 
Simply Easy Learning.

Example - Transfer data using IOUtils

CommonsIoTester.java

package com.tutorialspoint;

import java.io.FileWriter;
import java.io.IOException;

import org.apache.commons.io.IOUtils;

public class CommonsIoTester {
   public static void main(String[] args) {
      try (FileInputStream fis = new FileInputStream("input.txt");
         FileOutputStream fos = new FileOutputStream("output.txt")) {
         IOUtils.copy(fis, fos);
         System.out.println("Data transferred successfully.");
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

Output

It will print the following result −

Data transferred successfully.

You can check the content of output.txt file created in current directory as −

Welcome to TutorialsPoint. 
Simply Easy Learning.

Example - Writing String to Stream using IOUtils

CommonsIoTester.java

package com.tutorialspoint;

import java.io.FileWriter;
import java.io.IOException;

import org.apache.commons.io.IOUtils;

public class CommonsIoTester {
   public static void main(String[] args) throws IOException {
      try (FileWriter writer = new FileWriter("output.txt")) {
         IOUtils.write("Welcome to Tutorialspoint.", writer);
         IOUtils.write(System.lineSeparator(), writer);
         IOUtils.write("Simple Easy Learning.", writer);
         System.out.println("Content written to file.");
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

Output

It will print the following result −

Content written to file.

You can check the content of output.txt file created in current directory as −

Welcome to Tutorialspoint.
Simple Easy Learning.