Compare two string value

ReturnMethodSummary
intcompareTo(String anotherString)Compares two strings lexicographically.
intcompareToIgnoreCase(String str)Compares two strings lexicographically, ignoring case differences.
booleanequals(Object anObject)Compares this string to the specified object.
booleanequalsIgnoreCase(String anotherString)Compares this String to another String, ignoring case considerations.

The result of the compareTo(String anotherString) and compareToIgnoreCase(String str) is shown here:

ValueMeaning
Less than zeroThe invoking string is less than str.
Greater than zeroThe invoking string is greater than str.
ZeroThe two strings are equal.

public class Main {
  public static void main(String[] argv) {
    String str = "Java2s.com";
    String str2 = "java2s.com";
    System.out.println(str.compareTo(str2));
    System.out.println(str.compareToIgnoreCase(str2));

  }
}

The output:


-32
0

compareToIgnoreCase(String str) returns the same results as compareTo( ). It only ignores the case differences.


public class Main {

  public static void main(String args[]) {
    System.out.println("A".compareToIgnoreCase("a"));
  }
}
  

The output:


0

The following code checks the length of a string, then gets the fourth char out of the string object and compares these two string objects.


public class Main {
  public static void main(String args[]) {
    String strOb1 = "java2s.com";
    String strOb2 = "java2s.com";
    String strOb3 = strOb1;

    System.out.println("Length of strOb1: " + strOb1.length());
    System.out.println("Char at index 3 in strOb1: " + strOb1.charAt(3));

    if (strOb1.equals(strOb2))
      System.out.println("strOb1 == strOb2");
    else
      System.out.println("strOb1 != strOb2");

    if (strOb1.equals(strOb3))
      System.out.println("strOb1 == strOb3");
    else
      System.out.println("strOb1 != strOb3");
  }
}

This program generates the following output:


Length of strOb1: 10
Char at index 3 in strOb1: a
strOb1 == strOb2
strOb1 == strOb3

The comparison is case-sensitive.


public class Main {
  public static void main(String args[]) {
    String s1 = "Hello";
    String s2 = "Hello";
    String s3 = "Good-bye";
    String s4 = "HELLO";
    System.out.println(s1 + " equals " + s2 + " -> " +

    s1.equals(s2));
    System.out.println(s1 + " equals " + s3 + " -> " + s1.equals(s3));
    System.out.println(s1 + " equals " + s4 + " -> " + s1.equals(s4));
    System.out.println(s1 + " equalsIgnoreCase " + s4 + " -> " + s1.equalsIgnoreCase(s4));
  }
}
  

The output:



Hello equals Hello -> true
Hello equals Good-bye -> false
Hello equals HELLO -> false
Hello equalsIgnoreCase HELLO -> true
  

To compare igoring case, call equalsIgnoreCase( ). It has this general form:


boolean equalsIgnoreCase(String str)

str is the String object being compared with the invoking String object. Here is an example that demonstrates equals( ) and equalsIgnoreCase( ):


public class Main {
  public static void main(String args[]) {
    String s1 = "Hello";
    String s2 = "Hello";
    String s3 = "Good-bye";
    String s4 = "HELLO";
    System.out.println(s1 + " equals " + s2 + " -> " +

    s1.equals(s2));
    System.out.println(s1 + " equals " + s3 + " -> " + s1.equals(s3));
    System.out.println(s1 + " equals " + s4 + " -> " + s1.equals(s4));
    System.out.println(s1 + " equalsIgnoreCase " + s4 + " -> " + s1.equalsIgnoreCase(s4));
  }
}
  

The output from the program is shown here:


Hello equals Hello -> true
Hello equals Good-bye -> false
Hello equals HELLO -> false
Hello equalsIgnoreCase HELLO -> true
  
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