How to initialize PrintWriter array?

Question

I have to create n number of files. N is random but it will be in this range 1<=n<=7. When I run this program it gives NullPointException. file_num is number of files to be created. If I remove null from the first line it tells me to initialize the array.

PrintWriter[] writer=null;
for(int j=0;j<file_num;j++)
{
    System.out.println("J is "+j);
    writer[j] =new PrintWriter(new File("file"+(j+1)+".csv"));
}

but if I remove that, it won't even compile and ask me to initialize the array — carline, Jan 30 '20 at 11:39
_ask me to initialize the array..._ Of course it does. Read over java arrays again — B001ᛦ, Jan 30 '20 at 11:40

score 0 · Accepted Answer · answered Jan 30 '20 at 11:41

0

When I run this program it gives NullPointException.

That's because

 PrintWriter[] writer = null;

You should initialize writer array with new empty array of size file_num

PrintWriter[] writer = new PrintWriter[file_num];

answered Jan 30 '20 at 11:41

Mihai Alexandru-Ionut

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How to initialize PrintWriter array?

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