comparison with strings having white space

Question

Sorry if it's a silly question. I need to compare with a name which has three words separated by one white space. If the name is null or "This is Android" i would do something, otherwise i do something else. For example, is the following code right to do this comparison?

 if((name==null)||(name.equalsIgnoreCase("This is Android")))
     { 
      //start activity 1
      }
    else 
      {
        //start activity 2
       }

Solution 1

You should check if the name is null before you do that, otherwise it looks good. (except for, it should be if instead of If):

//either
if(name != null) {
    if(name.equalsIgnoreCase("This is Android") {

    }
}

//or
if("This is Android ".equalsIgnoreCase(name)) {

Update:

When you are comparing strings, the whitespaces count. So, basically "Hello world" and "Hello world " are not equal.

You need to use the .trim() method to ignore the surrounding whitespaces.

name = name.trim(); //since strings are immutable you need to assign return value to name
if("This is Android".equalsIgnoreCase(name)) { 

Solution 2

"This is Android " is different from "This is Android" and equalsIgnoreCase will return false. You can use trim() to remove spaces and the start or the end of the Strings.

Hope this helps!

Solution 3

Always keep constant String on left hand side in equals, this ensures no NPE:

like this :

if ("This is Android ".equalsIgnoreCase(str1)) {
    // start activity 1
} else {
    // start activity 2
}

In case you dont want space then add trim():

if ("This is Android ".trim().equalsIgnoreCase(str1)) {
     // start activity 1
} else {
     // start activity 2
}

Solution 4

if("This is Android".equalsIgnoreCase(name))
    // start activity 1
} else {
    // start activity 2
}

or the bullet-proof (in case user pasted value with unwanted spaces at the end of string)

if(name != null && "This is Android".equalsIgnoreCase(name.trim()))
    // start activity 1
} else {
    // start activity 2
}

View more solutions

Comments

[Miquel]

Why do you go toString on a String literal? Also, why invert the order?

[Bhesh Gurung]

@Miquel: Thanks for spotting. Did not pay attention while copy from OP. If you invert if the null check is not required so.

[Chris Aldrich]

@gurung - unless there is a need, you do not need to check for null. That is covered by the equalsIgnoreCase call.

[kzs]

actually "This is Android" in the code. is what i meant...edited my question again..sorry for the typo.

[Bhesh Gurung]

@ChrisAldrich: That does not make any sense. Suppose: name is null then how is equalsIgnoreCase going to cover name.equalsIgnoreCase??? It's that simple.

[Dimitris Makris]

Then the answer is yes. The comparison is ok.

[viktor]

I would never use string != null string.equals("literal") and its variants. It's bad practice and it should not be even mentioned.