This the second post for Java string methods. In this post I will detail more functions and its functionalities.
matches()
This method tests string against given regular expression. This method returns true only if this string matches the given regular expression.
Syntax:
public boolean matches(String regex)
regex the regular expression.
Example:
public class Sample { public static void main(String args[]) { String Str = new String("Hello Visitor in SamiElkady.com"); System.out.println(Str.matches("(.*)Sami(.*)")); System.out.println(Str.matches("^Hello(.*)")); System.out.println(Str.matches("^H[a-z]+(.*)")); System.out.println(Str.matches("^([A-Za-z]+)")); } }
Result:
true true true false
regionMatches()
This method has two different formats with different inputs (pramters) which can be used to test if two string regions are equal. It returns true if the specified subregion of this string matches the specified region of the string argument.
Syntax:
public boolean regionMatches(int i, string str, int o, int len);
OR
public boolean regionMatches(boolean ign, int i, String str, int o, int len);
i the starting offset of the subregion in this string.
str the string argument.
o the starting offset of the subregion in the string argument.
len the number of characters to compare.
ign if true, ignore case when comparing characters.
Example:
public class sample{ public static void main(String args[]){ String Str1 = new String("Hello Visitor in SamiElkady.com"); String Str2 = new String("SamiElkady"); String Str3 = new String("SAMIELKADY"); System.out.println(Str1.regionMatches(17, Str2, 0, 10)); System.out.println(Str1.regionMatches(17, Str3, 0, 10)); System.out.println(Str1.regionMatches(true, 17, Str3, 0, 10)); } }
Result:
true false true
replace()
This method searches for a character and repace it with new character creating new string by replacing all occurrences of oldChar in this string with newChar.
Syntax:
public String replace(char oldChar, char newChar);
oldChar the old character to be replaced.
newChar the new character.
Example:
public class Sample{ public static void main(String args[]){ String Str = new String("Hello Samy"); System.out.println(Str.replace('y', 'i')); } }
Result:
Hello Sami
replaceAll()
This method replaces each substring of this string that matches the given regular expression with the given replacement.
Syntax:
public String replaceAll(String regex, String str);
regex the regular expression to which this string is to be matched.
str the string which would replace found expression.
Example:
public class Sample{ public static void main(String args[]){ String Str = new String("Hello Sami"); System.out.println(Str.replaceAll("(Sami)", "John" )); } }
Result:
Hello John
replaceFirst()
This method replaces the first substring of this string that matches the given regular expression with the given replacement.
Syntax:
public String replaceFirst(String regex, String replacement);
regex the regular expression to which this string is to be matched.
replacement the string which would replace found expression.
Example:
public class Sample{ public static void main(String args[]){ String Str = new String("Hello John and John"); System.out.println(Str.replaceFirst("John", "Sami" )); } }
Result:
Hello Sami and John
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