toLowerCase() and toUpperCase()

If we want to convert all string characters into lower case or upper case, we can use these methods.

toLowerCase()

This method returns the string with all the characters converted into lower case if any in upper case.

There are 2 overloaded methods in toLowerCase()

One which takes locale and one which does not.

Signature of the methods

public String toLowerCase()

public String toLowerCase(Locale locale)

public String toLowerCase()

This method returns a new string by Converting all the characters in this String to lower case (using the default locale)

Example

public class StringLowerExample1{  
public static void main(String args[]){  
String str="JAVAinsimpleWAY";  
String strLower=str.toLowerCase();  
System.out.println(strLower);  
}
}

Output

Javainsimpleway

public String toLowerCase(Locale locale)

This method returns a new string by Converting all the characters in this String to lower case according to the given locale

Example

import java.util.Locale;
public class StringLowerExample2{  
public static void main(String args[]){  
String str="JAVAinsimpleWAY";  
String strLower=str.toLowerCase(Locale.ENGLISH);  
System.out.println(strLower);  
}
}

Output

Javainsimpleway

Note:

Since case mappings in different locales are not always 1:1 char mappings, the resulting String may be a different length than the original String.

toUpperCase()

This method returns the string with all the characters converted into Upper case if any in lower case.

There are 2 overloaded methods in toUpperCase()

One which takes locale and one which does not.

Signature of the methods

public String toUpperCase()

public String toUpperCase(Locale locale)

public String toUpperCase ()

This method returns a new string by Converting all the characters in this String to upper case (using the default locale)

Example

public class StringUpperExample1{  
public static void main(String args[]){  
String str="JAVAinsimpleWAY";  
String strUpper=str.toUpperCase();  
System.out.println(strUpper);  
}
}

Output

JAVAINSIMPLEWAY

public String toUpperCase(Locale locale)

This method returns a new string by Converting all the characters in this String to upper case according to the given locale

Example

import java.util.Locale;
public class StringUpperExample2{ 
public static void main(String args[]){  
String str="JAVAinsimpleWAY";  
String strUpper=str.toUpperCase (Locale.ENGLISH);  
System.out.println(strUpper);  
}
}

Output

JAVAINSIMPLEWAY

Note:

Since case mappings in different locales are not always 1:1 char mappings, the resulting String may be a different length than the original String.

Raj

Founder of javainsimpleway.com
I love Java and open source technologies and very much passionate about software development.
I like to share my knowledge with others especially on technology 🙂
I have given all the examples as simple as possible to understand for the beginners.
All the code posted on my blog is developed,compiled and tested in my development environment.
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