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How to merge multiple files into one in Kotlin

How to merge multiple files into one in Kotlin.

Here's a step-by-step tutorial on how to merge multiple files into one in Kotlin:

Step 1: Create the input files​

First, you need to create the input files that you want to merge. For this tutorial, let's assume you have three text files named file1.txt, file2.txt, and file3.txt. Make sure these files exist in the same directory as your Kotlin code.

Step 2: Open the output file​

Next, you need to open the output file where you will merge the contents of the input files. In Kotlin, you can use the FileWriter class to create the output file. Here's an example:

import java.io.FileWriter

fun main() {
    val outputFile = FileWriter("output.txt", true)
}

In this example, we create an instance of FileWriter and pass the name of the output file (output.txt) as the constructor argument. The second argument true indicates that we want to append the contents to the existing file (if any).

Step 3: Read the input files​

Now, you need to read the contents of the input files one by one. In Kotlin, you can use the readText() function to read the entire contents of a file as a string. Here's an example:

import java.io.File

fun main() {
    val outputFile = FileWriter("output.txt", true)
    
    val inputFiles = listOf("file1.txt", "file2.txt", "file3.txt")
    
    for (inputFile in inputFiles) {
        val content = File(inputFile).readText()
        
        // Write the contents to the output file
        outputFile.write(content)
    }
}

In this example, we create a list inputFiles that contains the names of the input files. Then, we loop through each input file, read its contents using File(inputFile).readText(), and write the contents to the output file using outputFile.write(content).

Step 4: Close the output file​

Finally, you need to close the output file to ensure that all the contents are properly written. In Kotlin, you can use the close() function of the FileWriter class. Here's the updated example:

import java.io.FileWriter

fun main() {
    val outputFile = FileWriter("output.txt", true)
    
    val inputFiles = listOf("file1.txt", "file2.txt", "file3.txt")
    
    for (inputFile in inputFiles) {
        val content = File(inputFile).readText()
        
        // Write the contents to the output file
        outputFile.write(content)
    }
    
    outputFile.close()
}

In this example, we added outputFile.close() at the end to close the output file.

That's it! You have successfully merged multiple files into one using Kotlin. The merged contents will be saved in the output.txt file.