java process multiple string arguments

Question

I have the following code in java:

public void loadFiles(String file_1, String file_2) throws FileNotFoundException, IOException {

    String line_file1;
    String line_file2;
    BufferedReader buf_file1 = new BufferedReader(new FileReader(new File(file_1)));
    BufferedReader buf_file2 = new BufferedReader(new FileReader(new File(file_2)));

}

Now when he runs this process, he expects both a file_1 and file_2. But I also want to make it go through when there is only a file_1. How should I specify this?

public void loadFiles(String... files)

SMA
– SMA

2016-06-23 08:06:05 +00:00
Commented Jun 23, 2016 at 8:06 — SMA
– SMA, Commented Jun 23, 2016 at 8:06

Eran · Accepted Answer · 2016-06-23 08:23:20Z

4

You can use varargs :

public void loadFiles(String... fileNames) throws FileNotFoundException, IOException {
    BufferedReader[] buf_file = new BufferedReader[fileNames.length];
    for (int i = 0; i < fileNames.length; i++) {
        buf_file[i] = new BufferedReader(new FileReader(new File(fileNames[i])));
    }
}

Which allows your method to be called with any number of file names :

loadFiles("a.txt");
loadFiles("a.txt", "b.txt");
...

No need for unnecessary method overloading when there's a simple alternative.

edited Jun 23, 2016 at 8:23

answered Jun 23, 2016 at 8:05

Eran

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2 Comments

user1987607 Over a year ago

Mhm, I don't understand. I should then nowhere specify 'file_1' and 'file_2'? I will make an edit to the original post, to clarify the situation better

Eran Over a year ago

@user1987607 Instead of file_1 and file_2, you have fileNames[0], fileName[1], etc... (which you can iterate over in a loop, as shown in my answer).

MysticForce · Accepted Answer · 2016-06-23 08:06:42Z

2

Java doesn't support default values to arguments or skipping the arguments . This is exactly where overloading comes into picture

define another method

public void loadFiles(String file_1) throws FileNotFoundException, IOException {

...

}

answered Jun 23, 2016 at 8:06

MysticForce

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Comments

Community · Accepted Answer · 2017-05-23 10:29:52Z

0

As said by Eran, "..." (Spread operator accepts 'n' arguments). This is kind of similar to list of array arguments (E.g., main(String args[])). Spread operator(...) has been introduced in Java 8. However, for your better understanding a simple example demonstrating the '...' spread operator as below

public class TestClass {

public static void test(String... args){
    for(String str: args){
        System.out.println(str);
    }
}
public static void main(String[] args) {
    // TODO Auto-generated method stub
    test("a","m","a", "r");
}

}

edited May 23, 2017 at 10:29

CommunityBot

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answered Jun 23, 2016 at 9:16

Amar

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