How to chain multiple different InputStreams into one InputStream in java

How to chain multiple different InputStreams into one InputStream in java

In Java, you can chain multiple different InputStream objects into one using SequenceInputStream or by manually implementing a custom InputStream. Here are two approaches:

Using SequenceInputStream:

SequenceInputStream is a built-in Java class that allows you to concatenate multiple input streams together. Here's how you can use it:

import java.io.*; import java.util.Vector; public class ChainedInputStreamExample { public static void main(String[] args) throws IOException { // Create InputStreams to be chained InputStream inputStream1 = new ByteArrayInputStream("Hello, ".getBytes()); InputStream inputStream2 = new ByteArrayInputStream("world!".getBytes()); // Create a Vector of InputStreams Vector<InputStream> inputStreams = new Vector<>(); inputStreams.add(inputStream1); inputStreams.add(inputStream2); // Create a SequenceInputStream to chain the input streams SequenceInputStream chainedInputStream = new SequenceInputStream(inputStreams.elements()); // Read from the chained input stream int data; while ((data = chainedInputStream.read()) != -1) { System.out.print((char) data); } // Close the chained input stream (this will also close the underlying streams) chainedInputStream.close(); } }

In this example, we create two InputStream objects (inputStream1 and inputStream2) and chain them together using SequenceInputStream. The data from both streams is read and printed.

Using a custom InputStream:

You can also create a custom InputStream class to chain multiple input streams manually. Here's an example of how to do it:

import java.io.IOException; import java.io.InputStream; public class ChainedInputStream extends InputStream { private final InputStream[] inputStreams; private int currentStreamIndex = 0; public ChainedInputStream(InputStream... inputStreams) { this.inputStreams = inputStreams; } @Override public int read() throws IOException { while (currentStreamIndex < inputStreams.length) { int data = inputStreams[currentStreamIndex].read(); if (data != -1) { return data; } else { currentStreamIndex++; } } return -1; } @Override public void close() throws IOException { for (InputStream inputStream : inputStreams) { inputStream.close(); } } }

With this custom ChainedInputStream, you can chain multiple input streams together and read from them as if they were a single stream.

Here's how to use the custom ChainedInputStream:

public class ChainedInputStreamExample { public static void main(String[] args) throws IOException { InputStream inputStream1 = new ByteArrayInputStream("Hello, ".getBytes()); InputStream inputStream2 = new ByteArrayInputStream("world!".getBytes()); ChainedInputStream chainedInputStream = new ChainedInputStream(inputStream1, inputStream2); int data; while ((data = chainedInputStream.read()) != -1) { System.out.print((char) data); } chainedInputStream.close(); } }

Both of these methods allow you to chain multiple InputStream objects into one, enabling you to read from them sequentially as if they were a single stream. Choose the method that best suits your requirements and coding style.

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