Java Class getResourceAsStream() Method

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Description

The Java Class getResourceAsStream() method finds a resource with a given name.It returns a InputStream object or null if no resource with this name is found.

Declaration

Following is the declaration for java.lang.Class.getResourceAsStream() method

public InputStream getResourceAsStream(String name)

Parameters

name − This is the name of the desired resource.

Return Value

This method returns a InputStream object or null if no resource with this name is found.

Exception

NullPointerException − If name is null.

Getting Stream of a Resource Example

The following example shows the usage of java.lang.Class.getResourceAsStream() method. In this program, we've created an instance of ClassDemo and then using getClass() method, the class of the instance is retrieved. Using getResourceAsStream(), we've retrieved the stream from a name of a file and printed the content of the same.

package com.tutorialspoint;

import java.io.*;

public class ClassDemo {

   static String getResource(String rsc) {
      String val = "";

      try {
         // input stream
         InputStream i = ClassDemo.class.getResourceAsStream(rsc);
         BufferedReader r = new BufferedReader(new InputStreamReader(i));

         // reads each line
         String l;
         while((l = r.readLine()) != null) {
            val = val + l;
         } 
         i.close();
      } catch(Exception e) {
         System.out.println(e);
      }
      return val;
   }
    
   public static void main(String[] args) {

      System.out.println("File1: " + getResource("file.txt"));
      System.out.println("File2: " + getResource("test.txt"));                
   }
} 

Output

Assuming we have a text file file.txt, which has the following content −

This is TutorialsPoint!

Assuming we have another text file test.txt, which has the following content −

This is Java Tutorial

Let us compile and run the above program, this will produce the following result −

File1: This is TutorialsPoint!
File2: This is Java Tutorial

Getting Stream of a Non-Existing Resource Example

The following example shows the usage of java.lang.Class.getResourceAsStream() method. In this program, we've created an instance of ClassDemo and then using getClass() method, the class of the instance is retrieved. Using getResourceAsStream(), we've retrieved the stream from a name of a file and printed the content of the same.

package com.tutorialspoint;

import java.io.*;

public class ClassDemo {

   static String getResource(String rsc) {
      String val = "";

      try {
         // input stream
         InputStream i = ClassDemo.class.getResourceAsStream(rsc);
         BufferedReader r = new BufferedReader(new InputStreamReader(i));

         // reads each line
         String l;
         while((l = r.readLine()) != null) {
            val = val + l;
         } 
         i.close();
      } catch(Exception e) {
         System.out.println(e);
      }
      return val;
   }
    
   public static void main(String[] args) {

      System.out.println("File1: " + getResource("file1.txt"));
      System.out.println("File2: " + getResource("test1.txt"));                
   }
} 

Output

Let us compile and run the above program, this will produce the following result −

java.lang.NullPointerException
File1: 
java.lang.NullPointerException
File2: