How to check empty spaces in java

Question

String selectedVal = "";

for (SelectItem item : filterItems) {
                selectedVal = item.getValue().toString();
                break;
            }

I am getting selectedVal=" " how to check this empty space in java.

I tried with if(!selectedVal.equals("") and if(!selectedVal.isEmpty()) but condition getting true.How to check more than one empty space ?

Colin Hebert · Accepted Answer · 2010-09-19 11:11:44Z

9

You can trim() your string before checking with isEmpty()

boolean isEmpty = myString.trim().isEmpty();

Beware of isEmpty(), it's only available since Java SE 6

Resources :

answered Sep 19, 2010 at 11:11

Colin Hebert

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1 Comment

helpermethod Over a year ago

If isEmpty() is not available, you can also check the String length: if (s.length() == 0) {}

Grodriguez · Accepted Answer · 2010-09-19 12:03:12Z

8

I use this all the time:

public static boolean isBlank(String s)
{
    return (s == null) || (s.trim().length() == 0);
}

Returns true on null, empty string, or whitespace only.

answered Sep 19, 2010 at 12:03

Grodriguez

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Comments

Benoit Courtine · Accepted Answer · 2010-09-19 12:04:47Z

2

For such a simple test, using an external library is not a good idea, but if you need String manipulation (left and right padding, etc.), you can go for Apache commons lang and the StringUtils.isEmpty() method.

More recently, you can use the Google Guava library and the class Strings. This library has a lot of usefull util methods (null handling, etc.). Once again, use this library only if you have others needs than checking empty strings.

answered Sep 19, 2010 at 12:04

Benoit Courtine

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jcrshankar · Accepted Answer · 2012-08-31 05:54:55Z

2

boolean isEmpty = myString.toString().trim().isEmpty()

answered Aug 31, 2012 at 5:54

jcrshankar

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Tony Ennis · Accepted Answer · 2010-09-19 12:21:29Z

1

I use a routine similar to what Grodriguez posted. It ends up in a util/BagOTricks.java file in every project. My routine does a similar check and returns a null as a space, or the trimmed input string.

answered Sep 19, 2010 at 12:21

Tony Ennis

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Shimmy Weitzhandler · Accepted Answer · 2010-09-19 13:40:14Z

0

I am not a java programmer, but with regex, \s means white space.

This link might also be useful:

 /**
   * Helper function for making null strings safe for comparisons, etc.
   *
   * @return (s == null) ? "" : s;
   */
  public static String makeSafe(String s) {
    return (s == null) ? "" : s;
  }

/**
   * Helper function for null, empty, and whitespace string testing.
   *
   * @return true if s == null or s.equals("") or s contains only whitespace
   *         characters.
   */
  public static boolean isEmptyOrWhitespace(String s) {
    s = makeSafe(s);
    for (int i = 0, n = s.length(); i < n; i++) {
      if (!Character.isWhitespace(s.charAt(i))) {
        return false;
      }
    }
    return true;
  }

edited Sep 19, 2010 at 13:40

answered Sep 19, 2010 at 11:10

Shimmy Weitzhandler

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5 Comments

Colin Hebert Over a year ago

Why regexes when you don't have a regular expression ?

Carl Smotricz Over a year ago

@Colin Hebert: He wants to test for a condition of "only space(s)." That's a classic 1:1 correspondence to a regexp, in my view. Especially if it turns out his data contains whitespace characters other than space. Shimmy's procedural solution probably works well enough and certainly has better performance, but it's far from an elegant translation of the problem.

dogbane Over a year ago

can you expand on what the makeSafe method does?

Shimmy Weitzhandler Over a year ago

I am not in the java business anyway, just googled around and that's what I've found, I am a .NET user where the IsNullOrWhiteSpace method is out-the-box (in .NET 4), otherwise I would've checked isnull->trim->length. Also in .NET there are extension methods which make the solution much more convenient.

Shimmy Weitzhandler Over a year ago

@fahd, as I said, I am not a java programmer at all, and as stated in my post, the code is taken from the link above it: java2s.com/Code/Java/Data-Type/Blankstringemptyorwhitespace.htm

dkero · Accepted Answer · 2017-09-05 07:50:29Z

0

You can use this method:

public boolean isNullOrEmpty(String s) {
    return s == null || s.trim().isEmpty();
}

Method returns true when passed string is null or empty / only contains blank spaces.

answered Sep 5, 2017 at 7:50

dkero

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Toby Peschel · Accepted Answer · 2018-02-06 03:14:27Z

0

Using the Apache Commons Lang library, you can use StringUtils.isEmpty() to check if a String is empty ("") or null, and StringUtils.isBlank() to check if a String is whitespace, empty ("") or null.

Note the differences:

isEmpty()

StringUtils.isEmpty(null)      = true
StringUtils.isEmpty("")        = true
StringUtils.isEmpty(" ")       = false
StringUtils.isEmpty("bob")     = false
StringUtils.isEmpty("  bob  ") = false

isBlank()

StringUtils.isBlank(null)      = true
StringUtils.isBlank("")        = true
StringUtils.isBlank(" ")       = true
StringUtils.isBlank("bob")     = false
StringUtils.isBlank("  bob  ") = false

answered Feb 6, 2018 at 3:14

Toby Peschel

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