String Comparison Styles in Java

String Comparison Styles

java - strings comparisons

Preface

In the former units, we've learned about working with strings, such as creating strings, comparing strings using the equivalency driver (==), etc.

In this unit, we will explore further ways to produce and compare strings in Java. To get started, let's learn how strings are actually created in Java, and also we will learn how to compare the strings using different string styles.

1. Creating Strings

In Java, strings can be created in two ways:

Using string literals
Using new keyword

Using String Literals

A string literal is a value enclosed in double quotations (""). In Java, a string literal is created using double quotations.

Illustration:

String str = "ABC";

Then, "ABC" is a string literal assigned to the variable str.

In Java, when strings are created using string literals with the same value, both the strings point to the same reference. As a result, memory can be saved during execution.

Using New Keyword

A string can be created by initializing the String class with the new keyword.

Syntax:

String str1 = new String("ABC");

Then, str is a string literal ("ABC").

When a string is created using the new keyword, the string is stored in a new memory location.

2. Comparing Strings

In Java, we can compare two strings in different ways. Some of them are listed below:

Using Equality (==) Operator
Using equals() Method
Using equalsIgnoreCase() Method
Using compareTo() Method
Using compareToIgnoreCase() Method

Using Equality (==) Operator

The == operator compares the strings based on their memory locations.

Illustration 1

Code:

class CompareStrings {
    public static void main(String[] args) {
        String str1 = "ABC";
        String str2 = "ABC";
        System.out.println(str1 == str2);
    }
}

Affair:

true

In the above example, str1 and str2 are created using a string literal, and they have the same reference. So, the output is true.

Illustration 2

Code:

class CompareStrings {
    public static void main(String[] args) {
        String str1 = new String("ABC");
        String str2 = new String("ABC");
        System.out.println(str1 == str2);
    }
}

Affair:

false

Here, str1 and str2 are created using the new keyword, meaning they point to different memory locations. So, == returns false even though they have the same value.

Thus, the == operator can only be used when comparing strings created using string literals, and it cannot be used for strings created with the new keyword.

To compare strings created with the new keyword, we use string comparison methods.

3. String Comparison Methods

equals() Method

The equals() method checks if a given string is equal to another string. It is case-sensitive.

Syntax:

str1.equals(str2);

Code:

class CompareStrings {
    public static void main(String[] args) {
        String str1 = "ABC";
        String str2 = "ABC";
        String str3 = new String("ABC");
        String str4 = new String("ABC");
        System.out.println(str1.equals(str2));
        System.out.println(str3.equals(str4));
        System.out.println(str1.equals(str3));
    }
}

Affair:

true  
true  
true

equalsIgnoreCase() Method

The equalsIgnoreCase() method works similarly to equals() but ignores case differences.

Syntax:

str1.equalsIgnoreCase(str2);

Code:

class CompareStrings {
    public static void main(String[] args) {
        String str1 = "ABC";
        String str2 = "abc";
        String str3 = new String("aBc");
        System.out.println(str1.equalsIgnoreCase(str2));
        System.out.println(str1.equalsIgnoreCase(str3));
    }
}

Affair:

true  
true

compareTo() Method

The compareTo() method compares two strings based on Unicode values.

Syntax:

str1.compareTo(str2);

Illustration 1

Code:

class CompareStrings {
    public static void main(String[] args) {
        String str1 = "ABC";
        String str2 = "ABC";
        System.out.println(str1.compareTo(str2));
    }
}

Affair:

Illustration 2

Code:

class CompareStrings {
    public static void main(String[] args) {
        String str1 = "A";
        String str2 = "B";
        System.out.println(str1.compareTo(str2));
    }
}

Affair:

-1

compareToIgnoreCase() Method

The compareToIgnoreCase() method works like compareTo(), but ignores case differences.

Syntax:

str1.compareToIgnoreCase(str2);

Code:

class CompareStrings {
    public static void main(String[] args) {
        String str1 = "AbC";
        String str2 = "aBc";
        System.out.println(str1.compareToIgnoreCase(str2));
    }
}

Affair:

4. Comparing Characters

We can compare characters using relational operators such as ==, >, and <.

Illustration 1

Code:

class CompareCharacters {
    public static void main(String[] args) {
        System.out.println('A' < 'B');
    }
}

Affair:

true

Illustration 2

Code:

class CompareCharacters {
    public static void main(String[] args) {
        System.out.println('P' >= 'Q');
        System.out.println('H' == 'H');
    }
}

Affair:

false  
true



Related Posts :

        Java Introduction & Basics
         Sequence of Instructions in Java
         Java Data Types
         Java Input and Output Basics
         Java Type Conversions
         Java String Methods
         Java Logical Operators
         Conditional Statements in Java
         Java Ternary Operator
         Java Switch Statement
         Loops in Java
      Java String Method
          Chracters of Methods

         Unicode Variable Naming in Java

String Comparison Styles in Java