Java Answers Forum - Comparing Command-Line Arguments

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Comparing Command-Line Arguments

3 replies on 1 page. Most recent reply: Nov 21, 2005 12:21 AM by Matthias Neumair

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Joe Spoot

Posts: 4
Nickname: sllobb
Registered: Nov, 2005

Comparing Command-Line Arguments

Posted: Nov 18, 2005 9:26 AM

Ok, I want to usa a command-Line Argument in an if statement. However, when I write code such as:

if(args[0] == "-t")

it is always skipped. I realize now that it is comparing the argument's reference to -t. How do I make it compare the value?

Dave Hinton

Posts: 42
Nickname: catbells
Registered: Oct, 2003

Re: Comparing Command-Line Arguments

Posted: Nov 19, 2005 9:36 AM

Use equals(), e.g.,

if (args[0].equals("-t"))

java-samples.com Site

Posts: 1
Nickname: javasamp
Registered: Nov, 2005

Re: Comparing Command-Line Arguments

Posted: Nov 20, 2005 6:25 AM

Its always better to check if args[0] in not null before comparing its value.

Eg.
if(args[0] != null && args[0].equals("-t"))

Failing to do so may throw a null pointer exception if the value is null.

Matthias Neumair

Posts: 660
Nickname: neumi
Registered: Sep, 2003

Re: Comparing Command-Line Arguments

Posted: Nov 21, 2005 12:21 AM

'==' works only for primitive types.
If you use it for Objects, not the content will be compared, but the 'pointer' (C++ expression), the position in RAM will be compared.

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