Question

I have a String[] LinesFromFile which contains about 100 lines loaded from a file e.g.

LinesFromFile[0] is "Line1"

LinesFromFile[1] is "Line2"

LinesFromFile[2] is "Line3"

…

LinesFromFile[99] is "Line100"

I want to now create a new String[] SomeLinesFromFile and assign this variable some of the lines from LinesFromFile.

I would have thought it would have been as simple as:

String[] SomeLinesFromFile = null;
int offset = 45;

for (i = 0; i < 10, i++)
{
    SomeLinesFromFile[i] = LinesFromFile[offset + i];
}

I would have assumed this code would set SomeLinesFromFile[0] to SomeLinesFromFile[9] with the values of LinesFromFile[46] through to LinesFromFile[56].

When I try running this on my android device it crashes. What am I missing here?

Answer 1

String[] SomeLinesFromFile = null;

SomeLinesFromFile is null, so you cannot then do:

SomeLinesFromFile[i] = ...

You need to create an array first, e.g.:

String[] SomeLinesFromFile = new String[10];

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Incidentally, it is considered bad practice to name your variables starting with capital letters. So you should always use someLinesFromFile instead of SomeLinesForFile.