Java is rich with methods to handle strings and strings manipulation. In this post I will detail the most used string methods and usage of each one. As string functions are much and important I will make this post divided to several posts in a series to be easy to follow and to give time to exercise.
length()
This method Returns the length of the sequence of characters represented by this object.
Syntax:
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public int length(); |
Example:
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public class Sample{ public static void main(String args[]){ String Str1 = new String("Hello Sami"); String Str2 = new String("Welcome John" ); System.out.print("First String Length :" ); System.out.println(Str1.length()); System.out.print("Second String Length :" ); System.out.println(Str2.length()); } } |
Result:
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First String Length :10 Second String Length :12 |
substring()
This method has two deferent inputs one integer or two integer parameters as character indexes. The method with only one parameter returns a part of the string starting from the integer index. The method with only two parameters returns a part of the string starting from the first integer index and ends before the second index value.
Syntax:
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public String substring(int i) |
or
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public String substring(int i, int e) |
i the begin index, inclusive.
e the end index, exclusive.
Example:
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public class Sample{ public static void main(String args[]){ String Str = new String("Hello Sami"); System.out.println(Str.substring(6) ); System.out.println(Str.substring(6, 9) ); } } |
Result:
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Sami Sam |
toLowerCase()
This method changes the case condition of the characters to lower case condition. This functions have an optional parameter of the localization attribute used to convert to localized lowercase
Syntax:
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public String toLowerCase([Locale locale]) |
Example:
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public class Sample{ public static void main(String args[]){ String Str = new String("HELLO SAMI"); System.out.println(Str.toLowerCase()); } } |
Result:
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hello sami |
toUpperCase()
This method changes the case condition of the characters to upper case condition. This functions have an optional parameter of the localization attribute used to convert to localized uppercase.
Syntax:
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public String toUpperCase([Locale locale]) |
Example:
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public class Sample{ public static void main(String args[]){ String Str = new String("hello sami"); System.out.println(Str.toUpperCase() ); } } |
Result:
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HELLO SAMI |
toString()
Returns a string representation of the object. In general, the method returns a string that “textually represents” this object.
Syntax:
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public String toString() |
Example:
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public class Test { public static void main(String args[]) { String str1 = new String("Hello Sami"); System.out.println(str1.toString()); } } |
Result:
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Hello Sami |
trim()
This method returns a copy of the string, with removing leading and trailing whitespaces.
Syntax:
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public String trim() |
Example:
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public class Sample{ public static void main(String args[]){ String Str = new String(" Hello Sami "); System.out.println(Str.trim() ); } } |
Result:
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Hello Sami |