String.isBlank() replacement

Question

I'm trying to adapt a code which uses String.isBlank(text). This method was introduced in Java 11, but my current project uses Java 8 and I don't want to upgrade. Is there anywhere the source code of the isBlank method or how can I replace it?

I tried make a method but I'm not sure what check should I put in there:

/**
 * @param text - the text to check
 * @return {@code true} if {@code text} is empty or contains only white space codepoints
 */
public static final boolean isBlank(final String text)
{
    if (text == null || text.isEmpty())
    {
        return true;
    }
    
    for (final char c : text.toCharArray())
    {
        //Check here
    }
    
    return false;
}

Does this answer your question? [Difference between isEmpty() and isBlank() Method in java 11](https://stackoverflow.com/questions/51299126/difference-between-isempty-and-isblank-method-in-java-11) — Sudoss, Aug 12 '20 at 11:57
[You cannot add methods to the java string library as the class is final](https://stackoverflow.com/questions/81786/can-i-add-new-methods-to-the-string-class-in-java). Instead you should make your own method to use. — Conor Egan, Aug 12 '20 at 11:57

TheTisiboth · Answer 1 · 2020-08-12T12:03:34.760

5

In the class org.apache.commons.lang3.StringUtils, the function isBlank is like this:

public static boolean isBlank(final CharSequence cs) {
    int strLen;
    if (cs == null || (strLen = cs.length()) == 0) {
        return true;
    }
    for (int i = 0; i < strLen; i++) {
        if (!Character.isWhitespace(cs.charAt(i))) {
            return false;
        }
    }
    return true;
}

It works well for Java 8, you just have to import it

edited Aug 12 '20 at 12:03

answered Aug 12 '20 at 11:55

TheTisiboth

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So this should be fine right? https://justpaste.it/4tzn8 – KbantikiMixaniki Aug 12 '20 at 11:59
Also return true; at the end of the method instead of false. Ops – KbantikiMixaniki Aug 12 '20 at 12:00
But why you don't use the isBlank method that i just showed you? You just have to import it, it is in a public library ;) – TheTisiboth Aug 12 '20 at 12:01
Our method are the same.Im sorry – KbantikiMixaniki Aug 12 '20 at 12:03
Yes, it seems that they are likely the same – TheTisiboth Aug 12 '20 at 12:04

score 3 · Answer 2 · answered Aug 12 '20 at 12:22

3

Before Java 11: string.trim().isEmpty();

so, if you want wrap isBlank function, you can do as follow:

public static final boolean isBlank(final String text) {
    return text == null || text.trim().isEmpty();
}

answered Aug 12 '20 at 12:22

Halayem Anis

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score 1 · Answer 3 · answered Aug 12 '20 at 12:08

I had the same issue that you, a Java 11 project which I had to downgrade to Java 8. You can import Apache Commons in your project:

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.9</version>
</dependency>

Then only what you need to do is call StringUtils.isBlank(string) it will return true or false

score 0 · Answer 4 · answered Aug 12 '20 at 11:58

0

You can use Guava library, and

Strings.nullToEmpty(str).trim().isEmpty()

to replicate the isBlank behaviour.

answered Aug 12 '20 at 11:58

merc-angel

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score 0 · Answer 5 · answered Aug 12 '20 at 12:06

In addition to other answers (importing libraries), you can define your own function in a StringUtils class, then you can add any other String utils operations.

The current method you want would look like this:


public static boolean isNullOrEmpty(String text) {
        boolean isNull = true;
        if (text != null) {
            if (!text.trim().equals("")) {
                isNull = false;
            }
        }
        return isNull;
    }

Also, through this you don't have to import any library

String.isBlank() replacement

5 Answers5