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how to subtract two strings  RSS feed

 
preethi Ayyappan
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Hi,

I am having a string variable,say
String a="30"
and another string variable
String b="1"
.

Now i need to subtract 1 from 30.How do i subtract these two things.
please assist me to do this.

Thanks
 
Seetharaman Venkatasamy
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Convert String to int [premitive]
 
Harshit Rastogi
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you can use


to parse the value..
 
Seetharaman Venkatasamy
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Harshit Rastogi wrote:you can use


to parse the value..


return type of the valueOf is wrapper(Integer) . this wont be much flexible in terms of mathematical operations .

if i were in your place, i would go for

 
Harshit Rastogi
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return type of the valueOf is wrapper(Integer) .


if jdk1.5 is used it doesnt matter because of autoboxing
 
Seetharaman Venkatasamy
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Harshit Rastogi wrote:if jdk1.5 is used it doesnt matter because of autoboxing


yes. true...
 
Rob Spoor
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Still, Integer.parseInt is more efficient because it doesn't create a new Integer object, which Integer.valueOf will do.
 
Jesper de Jong
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Rob Prime wrote:Still, Integer.parseInt is more efficient because it doesn't create a new Integer object, which Integer.valueOf will do.

The method Integer.valueOf(int i) uses a cache if i is between -128 and 127, so it doesn't create a new object if the value is between those boundaries. So I thought you were incorrect when you said that Integer.valueOf(String s) always creates a new object. I checked out the source code of class Integer (available in src.zip in the JDK directory), and to my surprise saw this:

So indeed, the method that takes a String always creates a new Integer object - you were right.

I wonder why this is - why did the people who programmed the JDK not write it like this?

Strange! But you know, the standard Java library isn't perfect...
 
It is sorta covered in the JavaRanch Style Guide.
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