Convert InputStream to BufferedReader

java

io-exceptions

bufferedreader

inputstream

byNikita Barsukov·Oct 25, 2024

To convert an InputStream into a BufferedReader for line-by-line reading, just wrap it using an InputStreamReader and then a BufferedReader:

InputStream inputStream = ...; // your input stream here
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8));

Crucial points to note:

Use InputStreamReader as the bridge between the two.
Specify UTF_8 as the charset for universal compatibility.
The BufferedReader will enable efficient processing of text.

Selecting the right character encoding

The code above prescribes UTF-8 by default, which should suffice for the majority of the cases. However, if you are dealing with different encodings, it's essential to specify the right Charset:

BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.ISO_8859_1));

Choosing the appropriate charset prevents messed up text:

UTF-8: For most languages and a safe default.
ISO_8859_1: Good for Western European texts.
US-ASCII: Only if your text is pure English.

Handling exceptions like a pro

InputStreams and BufferedReaders are notorious for throwing exceptions, so always enclose your code within try-catch blocks to handle IOExceptions:

try {
    InputStream inputStream = ...;
    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8));
      
    // Imagine being here, reading all your favorite books line by line, and then... Boom! An IOException happens! Wouldn't it ruin your day?
} catch (IOException exception) {
    exception.printStackTrace();
    // Deal with the exception here
}

Take a proactive approach to handling exceptions, and your code will thank you for it.

Getting efficient with BufferedReader reading

BufferedReader is optimized for efficient reading of characters, arrays, and lines. Here's how you can leverage these features:

Read line by line using the method readLine() to reduce I/O operations.
Adjust the buffer size based on your requirements:

int bufferSize = 8192; // Enough? Too small? Too big? Adjust accordingly.
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8), bufferSize);

Close all resources to prevent leaks in a finally block or by using try-with-resources.

Adapting to diverse application needs

Not all applications are created equal, and converting InputStream to BufferedReader can be modified according to your needs:

Network streams: Special handling is required to cope with network latency.
File streams: Here, you should use FileInputStream to wrap into BufferedReader.

FileInputStream fis = new FileInputStream("file.txt"); // Because you can't drink directly from a bottle, right?
BufferedReader reader = new BufferedReader(new InputStreamReader(fis, StandardCharsets.UTF_8));