Writing an entire list to a file in java

Question

I am working on a big project where I have more than 1 million lines of data. Data is divided into various files containing 20,000 lines each. Now the data from each file is read line by line and some variable x is concatenated to each line. I am storing these concatenated string to an array list. Then this array list is saved to output files line by line. This is taking 3-4 minutes on each file. Is there anyway to write the entire `ArrayList` to a file in one go, so that it won't take that much time. Or is there any faster way to do this? Here is some sample code: ``` List outputData = new ArrayList(); //Output arraylist containing concatenated data writeLines(File outputFile,outputData); //The data is written to file ``` What would be the fastest way to achieve this task?

Accepted Answer

Once you have the `ArrayList` ready you can use the `writeLines` method from `FileUtils` to write the entire `ArrayList` in one go.

Have a look at the documentation here and the various `writeLines` methods that are available.

Writing an entire list to a file in java

Solution

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