Null String or not Null String?

Question

I'm trying to get a string value from external file with this method:

File file = new File(name);
    BufferedReader br = new BufferedReader(new FileReader(file));
    String line = br.readLine();
    br.close();

And I have some lines that are equal to "null". But if I compare them to null or "null", or even to "", I get FALSE. What am I doing wrong?

How do you compare them? That's the relevant code. (Also, what is in the line, "null", null, empty string, or you really are getting the java null value? — Amadan
– Amadan, Commented Mar 28, 2016 at 4:03
Don't you need a loop to traverse through all the lines present in file. Right now it should be returining just first line and ending. — Himanshu Bhardwaj
– Himanshu Bhardwaj, Commented Mar 28, 2016 at 4:04
How some the lines can be null? It may be empty instead. — Shree Krishna
– Shree Krishna, Commented Mar 28, 2016 at 4:29
I don't know what I am getting from file. There is actually string "null" value, but if i compare it to string, it also returns false — GuyInSombrero
– GuyInSombrero, Commented Mar 28, 2016 at 4:47

Aaron Esau · Accepted Answer · 2016-03-28 19:30:18Z

3

If you want to check the null or not then you can check like this way:

String a;
if(a!=null) {}

Or, if you want to compare two string are equivalent or no, then you can give condition like:

 String a="hello";
 if(a.equals("hello")) {}

If you get null then you must check if the result is null or not. You can do it like this:

if(result!=null && !result.equals("")) {


}

If the result is null then next condition will not check and your issue will solve.

edited Mar 28, 2016 at 19:30

Aaron Esau

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answered Mar 28, 2016 at 5:20

Pravin Fofariya

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Comments

mmuzahid · Accepted Answer · 2016-03-28 04:14:39Z

2

I guess you are trying to compare with equals method. in equal method if the parameter is null then it will return false. Use == operator instead.

edited Mar 28, 2016 at 4:14

mmuzahid

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answered Mar 28, 2016 at 4:07

stinepike

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