$show=/label

Java String regionMatches​() Method Example

SHARE:

Quick guide to Java String API regionMatches​() Method with Examples. This method is used to compare two sub strings. Syntax: public boolean regionMatches​(int toffset, String other, int ooffset, int len)

1. Java String regionMatches​() Overview


In this tutorial, We'll learn about Java String API regionMatches​() method to compare two substrings. In other words, comparing regions of two strings.

This method is very handy when we want to compare portions of two strings. Instead of comparing all contents of Strings.

In previous article, We've discussed on String matches() method.

Java String API regionMatches​() Method Example


1.1 regionMatches() Syntax


public boolean regionMatches​(int toffset, String other, int ooffset, int len)
public boolean regionMatches​(boolean ignoreCase, int toffset, String other, int ooffset, int len)


Fist variant does case sensitive comparison
Second variant has option to ignore the case. If true, it ignores case when comparing.

Java String API regionMatches​()




1.2 Parameters


toffset - the starting offset of the subregion in this string.
other - the string argument.
ooffset - the starting offset of the subregion in the string argument.
len - the number of characters to compare.

1.3 Returns


boolean

true if the specified subregion of this string exactly matches the specified subregion of the string argument; false otherwise.

2. String regionMatches​() Examples


We'll write a example programs using regionMatches​() method. It is very important to pass the parameters in order and with required values.

2.1 regionMatches​() Method Example


Below example program is written on regionMatches​ method. For this method, we must have to pass the parameters as below.

1st parameter: Start index of the current string. Comparison will start from this point.
2nd parameter: Takes another string which is to be compared.
3rd parameter: Start index of the another string.
4th parameter: How many characters to be compared.

String str1 = "welcome to java-w3schools blog";
String otherStr = "java";
boolean isMatch = str1.regionMatches(11, otherStr, 0, 4);

if (isMatch) {
 System.out.println("Substrings are matched");
} else {
 System.out.println("Substrings are not matched");
}

Output:

Substrings are matched

2.2 Case Ignore regionMatches​() Method Example


The below program does compare substrings by ignoring Case Type. We need to pass the additional parameter to enable case ignore.

// Example 2: Case Ignore
String str2 = "WELCOME TO JAVA-W3SCHOOLS BLOG";
String otherStr2 = "java";
isMatch = str2.regionMatches(true, 11, otherStr2, 0, 4);

if (isMatch) {
 System.out.println("Substrings are matched");
} else {
 System.out.println("Substrings are not matched");
}

Observe the above program. A boolean value is passed in 1st parameter. This parameter tells to JVM to ignore case.

Output:


Substrings are matched


3. String regionMatches​() Internal Code

regionMatches() method internal implementation code shown below.

 public boolean regionMatches(int toffset, String other, int ooffset, int len) {
    byte tv[] = value;
    byte ov[] = other.value;
    // Note: toffset, ooffset, or len might be near -1>>>1.
    if ((ooffset < 0) || (toffset < 0) ||
         (toffset > (long)length() - len) ||
         (ooffset > (long)other.length() - len)) {
        return false;
    }
    if (coder() == other.coder()) {
        if (!isLatin1() && (len > 0)) {
            toffset = toffset << 1;
            ooffset = ooffset << 1;
            len = len << 1;
        }
        while (len-- > 0) {
            if (tv[toffset++] != ov[ooffset++]) {
                return false;
            }
        }
    } else {
        if (coder() == LATIN1) {
            while (len-- > 0) {
                if (StringLatin1.getChar(tv, toffset++) !=
                    StringUTF16.getChar(ov, ooffset++)) {
                    return false;
                }
            }
        } else {
            while (len-- > 0) {
                if (StringUTF16.getChar(tv, toffset++) !=
                    StringLatin1.getChar(ov, ooffset++)) {
                    return false;
                }
            }
        }
    }
    return true;
}

The result is false if and only if at least one of the following is true:

A) toffset is negative.
B) ooffset is negative.
C) toffset+len is greater than the length of this String object.
D) ooffset+len is greater than the length of the other argument.
E) There is some nonnegative integer k less than len such that: this.charAt(toffset + k) != other.charAt(ooffset + k)
   
Later it compares char by char. If char mismatch it returns true, otherwise returns false.

public boolean regionMatches(boolean ignoreCase, int toffset,
            String other, int ooffset, int len) {
        if (!ignoreCase) {
            return regionMatches(toffset, other, ooffset, len);
        }
        // Note: toffset, ooffset, or len might be near -1>>>1.
        if ((ooffset < 0) || (toffset < 0)
                || (toffset > (long)length() - len)
                || (ooffset > (long)other.length() - len)) {
            return false;
        }
        byte tv[] = value;
        byte ov[] = other.value;
        if (coder() == other.coder()) {
            return isLatin1()
              ? StringLatin1.regionMatchesCI(tv, toffset, ov, ooffset, len)
              : StringUTF16.regionMatchesCI(tv, toffset, ov, ooffset, len);
        }
        return isLatin1()
              ? StringLatin1.regionMatchesCI_UTF16(tv, toffset, ov, ooffset, len)
              : StringUTF16.regionMatchesCI_Latin1(tv, toffset, ov, ooffset, len);
    }

If ignoreCase is false then it calls regionMatches(toffset, other, ooffset, len). If it is true then calls StringLatin1.regionMatchesCI() for LATIN Character Set.
It calls StringUTF16.regionMatchesCI() for UTF Character Set.

4. Conclusion


In this article, We've seen what regionMatches() method does. And how to compare small portions of two strings.

Further in this article, discussed example program on how to ignore case while comparing.

Shown regionMatches() inernal implementation and how it works internally.

Example code snippets shown in this article is available on GitHub.


COMMENTS

BLOGGER

About Us

Author: Venkatesh - I love to learn and share the technical stuff.
Name

accumulo,1,ActiveMQ,2,Adsense,1,API,37,ArrayList,18,Arrays,24,Bean Creation,3,Bean Scopes,1,BiConsumer,1,Blogger Tips,1,Books,1,C Programming,1,Collection,8,Collections,37,Collector,1,Command Line,1,Comparator,1,Compile Errors,1,Configurations,7,Constants,1,Control Statements,8,Conversions,6,Core Java,149,Corona India,1,Create,2,CSS,1,Date,3,Date Time API,38,Dictionary,1,Difference,2,Download,1,Eclipse,3,Efficiently,1,Error,1,Errors,1,Exceptions,8,Fast,1,Files,17,Float,1,Font,1,Form,1,Freshers,1,Function,3,Functional Interface,2,Garbage Collector,1,Generics,4,Git,9,Grant,1,Grep,1,HashMap,2,HomeBrew,2,HTML,2,HttpClient,2,Immutable,1,Installation,1,Interview Questions,6,Iterate,2,Jackson API,3,Java,32,Java 10,1,Java 11,6,Java 12,5,Java 13,2,Java 14,2,Java 8,128,Java 8 Difference,2,Java 8 Stream Conversions,4,java 8 Stream Examples,12,Java 9,1,Java Conversions,14,Java Design Patterns,1,Java Files,1,Java Program,3,Java Programs,114,Java Spark,1,java.lang,4,java.util. function,1,JavaScript,1,jQuery,1,Kotlin,11,Kotlin Conversions,6,Kotlin Programs,10,Lambda,2,lang,29,Leap Year,1,live updates,1,LocalDate,1,Logging,1,Mac OS,3,Math,1,Matrix,6,Maven,1,Method References,1,Mockito,1,MongoDB,3,New Features,1,Operations,1,Optional,6,Oracle,5,Oracle 18C,1,Partition,1,Patterns,1,Programs,1,Property,1,Python,2,Quarkus,1,Read,1,Real Time,1,Recursion,2,Remove,2,Rest API,1,Schedules,1,Serialization,1,Servlet,2,Sort,1,Sorting Techniques,8,Spring,2,Spring Boot,23,Spring Email,1,Spring MVC,1,Streams,31,String,61,String Programs,28,String Revese,1,StringBuilder,1,Swing,1,System,1,Tags,1,Threads,11,Tomcat,1,Tomcat 8,1,Troubleshoot,26,Unix,3,Updates,3,util,5,While Loop,1,
ltr
item
JavaProgramTo.com: Java String regionMatches​() Method Example
Java String regionMatches​() Method Example
Quick guide to Java String API regionMatches​() Method with Examples. This method is used to compare two sub strings. Syntax: public boolean regionMatches​(int toffset, String other, int ooffset, int len)
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBti5ezjzml0M1EDsmsuIXanSyuAaTH9id9lRC5dH2KWxyPhIZ_AsrnxS9d16KJJ_D_w95l6xdr-N1qGDDe3PP-IRoT1qQ6ZRb3zt-raf0rxNMuLZy3bYyq38ATDv43WQBLmRBQmQ5Yb4/s320/Java+String+API+regionMatches%25E2%2580%258B%2528%2529+Method+Example.PNG
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBti5ezjzml0M1EDsmsuIXanSyuAaTH9id9lRC5dH2KWxyPhIZ_AsrnxS9d16KJJ_D_w95l6xdr-N1qGDDe3PP-IRoT1qQ6ZRb3zt-raf0rxNMuLZy3bYyq38ATDv43WQBLmRBQmQ5Yb4/s72-c/Java+String+API+regionMatches%25E2%2580%258B%2528%2529+Method+Example.PNG
JavaProgramTo.com
https://www.javaprogramto.com/2019/05/java-string-regionmatches.html
https://www.javaprogramto.com/
https://www.javaprogramto.com/
https://www.javaprogramto.com/2019/05/java-string-regionmatches.html
true
3124782013468838591
UTF-8
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS PREMIUM CONTENT IS LOCKED STEP 1: Share to a social network STEP 2: Click the link on your social network Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy Table of Content