How to Compare Strings In Groovy Script?

7 minutes read

In Groovy, you can compare strings using various operators and methods. Here are several ways to compare strings in a Groovy script:

  1. Using the equality operator (==): You can use the equality operator to check if two strings are equal. This operator returns a boolean value (true or false). For example:
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def str1 = "Hello"
def str2 = "World"
println(str1 == str2) // Prints 'false'


  1. Using the inequality operator (!=): Similar to the equality operator, the inequality operator allows you to check if two strings are not equal. For example:
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def str1 = "Hello"
def str2 = "World"
println(str1 != str2) // Prints 'true'


  1. Using the compareTo method: The compareTo method compares two strings lexicographically. It returns an integer indicating the comparison result. If the result is negative, the first string is lexicographically less than the second. If positive, it is greater. If zero, the strings are equal. For example:
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def str1 = "Apple"
def str2 = "Banana"
println(str1.compareTo(str2)) // Prints a negative value (-1 or less)


  1. Using the equals method: The equals method compares two strings for equality and returns a boolean value. This method considers both the content and case of the strings. For example:
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def str1 = "Hello"
def str2 = "hello"
println(str1.equals(str2)) // Prints 'false'


  1. Using the equalsIgnoreCase method: Similar to equals, the equalsIgnoreCase method compares two strings for equality, ignoring the case. For example:
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def str1 = "Hello"
def str2 = "hello"
println(str1.equalsIgnoreCase(str2)) // Prints 'true'


These are some of the common ways you can compare strings in Groovy. You can choose the appropriate method based on your specific comparison requirements.

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What is lexicographic ordering of strings in Groovy?

Lexicographic ordering of strings in Groovy refers to the ordering of strings based on their alphabetical order. It compares strings character by character, starting from the first character, until a difference is found. The first difference determines the order of the strings - the string with the lower character value in the differing position comes before the other string in the lexicographic ordering.


Here's an example of lexicographic ordering of strings in Groovy:

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def string1 = "apple"
def string2 = "banana"

int order = string1.compareTo(string2)
if (order < 0) {
    println("$string1 comes before $string2")
} else if (order == 0) {
    println("$string1 is equal to $string2")
} else {
    println("$string1 comes after $string2")
}


Output:

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apple comes before banana


In this example, "apple" is lexicographically ordered before "banana" because in the first differing position, 'a' comes before 'b'.


What is the behavior of comparing null strings in Groovy?

In Groovy, comparing null strings typically follows the behavior of comparing null values in Java. When comparing a null string to another value, such as a non-null string, boolean, or any other type, the result is usually false. This is because null is considered to be lower than any non-null value.


Here are a few examples in Groovy:

  1. Comparing null string to a non-null string:
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def nullString = null
def nonNullString = "example"
println nullString == nonNullString // Output: false


  1. Comparing null string to a boolean:
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def nullString = null
def booleanValue = true
println nullString == booleanValue // Output: false


  1. Comparing two null strings:
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def nullString1 = null
def nullString2 = null
println nullString1 == nullString2 // Output: true


It's important to note that when comparing null strings to other null values, Groovy typically follows the same behavior, returning true.


What is the null-safe string comparison technique in Groovy?

In Groovy, the null-safe string comparison technique is achieved by using the ==~ operator.


This operator can be used to compare two strings, even if one or both of them are null. It returns true if both strings are equal, and false otherwise. If one or both strings are null, it will consider them as empty strings for comparison.


Here's an example:

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def string1 = "Hello"
def string2 = null

println(string1 ==~ string2)  // Output: false


In the above example, string1 is "Hello" and string2 is null. The ==~ operator considers the null value as an empty string, so the comparison returns false.

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