What is StringUtils.getIfBlank in Java?

getIfBlank is a static method of the StringUtils class that works as follows:

  • The method takes in two arguments. One is the character sequence and the other is a supplier instance.
  • If the given character sequence is whitespace, empty, or null, then the method returns the value supplied by the supplier.
  • Otherwise, it returns the given character sequence.

Note: Supplier in Java 8 is a functional interface whose functional method is get(). The interface represents an operation that takes no arguments and returns a result.

StringUtils is defined in the Apache Commons Lang package. Apache Commons Lang can be added to the Maven project by adding the following dependency to the pom.xml file.

<dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.12.0</version>
</dependency>

Note: For other versions of the commons-lang package, refer to the Maven Repository.

You can import the StringUtils class as follows:

import org.apache.commons.lang3.StringUtils;

Syntax

public static <T extends CharSequence> T getIfBlank(T str, Supplier<T> defaultSupplier)

Parameters

  • T str: the string to check
  • Supplier<T> defaultSupplier: the supplier instance

Return value

The method returns the passed string or the value returned by the supplier.

Code

import org.apache.commons.lang3.StringUtils;
public class Main {
    public static void main(String[] args) {
        String string = "educative";
        String returnValue = StringUtils.getIfBlank(string, () -> "hello");
        System.out.printf("Value Returned for \"%s\" is \"%s\"", string, returnValue);
        System.out.println();
        string = "";
        returnValue = StringUtils.getIfBlank(string, () -> "hello");
        System.out.printf("Value Returned for \"%s\" is \"%s\"", string, returnValue);
        System.out.println();
        string = null;
        returnValue = StringUtils.getIfBlank(string, () -> "hello");
        System.out.printf("Value Returned for \"%s\" is \"%s\"", string, returnValue);
        System.out.println();
        string = "  ";
        returnValue = StringUtils.getIfBlank(string, () -> "hello");
        System.out.printf("Value Returned for \"%s\" is \"%s\"", string, returnValue);
        System.out.println();
    }
}

Example 1

  • string = "educative"
  • supplier function returns "hello"

The getIfBlank function returns educative.

Since the given string is not whitespace, null, or empty, the supplied character sequence is returned.

Example 2

  • string = ""
  • supplier function returns "hello"

The getIfBlank function returns hello.

Since the given string is an empty string, the method returns the value returned by the supplier.

Example 3

  • string = null
  • supplier function returns "hello"

The getIfBlank function returns hello.

Since the given string is null, the method returns the value returned by the supplier.

Example 4

  • string = " "
  • supplier function returns "hello"

The getIfBlank function returns hello.

Since the given string only has whitespace characters, the method returns the value returned by the supplier.

Expected output

Value Returned for "educative" is "educative"
Value Returned for "" is "hello"
Value Returned for "null" is "hello"
Value Returned for "  " is "hello"

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