How Can I Efficiently Read a Specific Line from a File in Java?

Reading Specific Lines from a File in Java

In Java, reading a particular line from a file can be achieved using various methods. This article explores two approaches to access specific lines based on their line numbers.

Small Files

For small text files, a straightforward solution involves reading all lines into a list and then retrieving the desired line using its index. The Files.readAllLines(Path) method can be used to read all the lines as follows:

String line32 = Files.readAllLines(Paths.get("file.txt")).get(32);

However, this approach is not efficient for large files as it loads the entire file into memory.

Large Files

For large files, an alternative method that avoids loading the complete file is using the skip() and findFirst() methods. Here, we skip the first n-1 lines and then retrieve the nth line:

try (Stream<String> lines = Files.lines(Paths.get("file.txt"))) {
    line32 = lines.skip(31).findFirst().get();
}

This approach is more efficient for large files as it streams the lines one by one, minimizing memory usage.

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