In this article, we will discuss regionMatches() method of String class which is used to check whether two substrings are same or NOT

1. String’s regionMatches() method:

This String method is used to check whether sub-string of invoking-string exactly matches sub-string of the specified string
Note: there are 2 variants or overloaded regionMatches() method

1.1 Method Signature:

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

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

1.2 Parameters:

toffset –> starting index-position for invoking string (or substring)
other –> another string (or substring) to which invoking string need to be compared
ooffset –> starting index-position for another string (or substring)
len –> number of characters to be compared (from another string)
ignoreCase –> if true, ignore case differences when comparing characters (applicable for 2^nd variant)

1.3 Note:

There are 2 strings
One is invoking string i.e.; original string
And another string
Sub-string from both original string & another string will be compared

1.4 Returns:

Returns true, if the sub-string of invoking-string exactly matches sub-string of the specified string (i.e.; both sub-string are same)
Returns false, if the sub-string of invoking-string doesn’t matches sub-string of the specified string (i.e.; both sub-string aren’t same)

2. Examples on regionMatches() method:

2.1 Example checks for exact matches between different strings

considers case-differences i.e.; case-sensitive
whereas, 2nd variant allows to specify whether we want to ignore or consider case-differences

StringRegionMatchesMethod.java

package in.bench.resources.string.methods;

public class StringRegionMatchesMethod {

	public static void main(String[] args) {

		// sample string values
		String originalStr = "This is Java World";
		String anotherStr = "Java";
		String anotherStr2 = "world"; // case-difference
		String anotherStr3 = "Another world is JEE"; // middle-str

		// 1st check for string 'Java'
		System.out.println(
			"originalStr(8, 4) ==  anotherStr(0, 4) : "
			+ originalStr.regionMatches(8, anotherStr, 0, 4));

		// 2nd check for string 'world' - case difference
		System.out.println("\n"
			+ "originalStr(13, 5) ==  anotherStr2(0, 5) : "
			+ originalStr.regionMatches(13, anotherStr2, 0, 5));

		// 3rd check for string 'is' - in middle of string
		System.out.println("\n"
			+ "originalStr(5, 2) ==  anotherStr3(14, 2) : "
			+ originalStr.regionMatches(5, anotherStr3, 14, 2));
	}
}

Output:

originalStr(8, 4) ==  anotherStr(0, 4) : true

originalStr(13, 5) ==  anotherStr2(0, 5) : false

originalStr(5, 2) ==  anotherStr3(14, 2) : true

2.2 This example very similar to above example but ignores case differences i.e.; case-insensitive

if 1^st parameter is kept false, then considers case-differences
otherwise if kept true, ignores case-differences (very similar to 1^st variant)

Note:

for considering case-differences, use 1^st variant
use 2^nd variant only when we want to ignore case-differences (by setting 1^st parameter as false)

StringRegionMatchesMethodForCase.java

package in.bench.resources.string.methods;

public class StringRegionMatchesMethodForCase {

	public static void main(String[] args) {

		// sample string values
		String originalStr = "This is Java World";
		String anotherStr = "Java";
		String anotherStr2 = "world"; // case-difference
		String anotherStr3 = "Another world IS J2ee";//middle-str

		// 1st check for string 'Java'
		System.out.println(""
				+ "originalStr(8, 4) ==  anotherStr(0, 4) "
				+ "considering case-difference   : "
				+ originalStr.regionMatches(
						false, 8, anotherStr, 0, 4));

		// 2nd check for string 'world'
		// considering case-difference
		System.out.println("\n"
				+ "originalStr(13, 5) ==  anotherStr2(0, 5) "
				+ "considering case-difference : "
				+ originalStr.regionMatches(
						false, 13, anotherStr2, 0, 5));

		// 3rd check for string 'world'
		// ignoring case-differences
		System.out.println("\n"
				+ "originalStr(13, 5) ==  anotherStr2(0, 5) "
				+ "ignoring case-difference    : "
				+ originalStr.regionMatches(
						true, 13, anotherStr2, 0, 5));

		// 3rd check for string 'is' - in middle of string
		System.out.println("\n"
				+ "originalStr(5, 2) ==  anotherStr3(14, 2) "
				+ "considering case-difference : "
				+ originalStr.regionMatches(
						false, 5, anotherStr3, 14, 2));
	}
}

Output:

originalStr(8, 4) ==  anotherStr(0, 4)
considering case-difference   : true

originalStr(13, 5) ==  anotherStr2(0, 5)
considering case-difference : false

originalStr(13, 5) ==  anotherStr2(0, 5)
ignoring case-difference    : true

originalStr(5, 2) ==  anotherStr3(14, 2)
considering case-difference : false

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References:

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Java tutorial for beginners

Java – String regionMatches() method

1. String’s regionMatches() method:

1.1 Method Signature:

1.2 Parameters:

1.3 Note:

1.4 Returns:

2. Examples on regionMatches() method:

2.1 Example checks for exact matches between different strings

StringRegionMatchesMethod.java

Output:

2.2 This example very similar to above example but ignores case differences i.e.; case-insensitive

Note:

StringRegionMatchesMethodForCase.java

Output:

Related Articles:

References:

Related

1. String’s regionMatches() method:

1.1 Method Signature:

1.2 Parameters:

1.3 Note:

1.4 Returns:

2. Examples on regionMatches() method:

2.1 Example checks for exact matches between different strings

StringRegionMatchesMethod.java

Output:

2.2 This example very similar to above example but ignores case differences i.e.; case-insensitive

Note:

StringRegionMatchesMethodForCase.java

Output:

Related Articles:

References:

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