Java Program to Change Case of a Character/String

Displaying Opposite Character: 

Logic:

  • First we should have to find the given case, for this you can use Character.isLowerCase(given character) or Character.isUpperCase(given character).
  • Once you know the given character then you can change to opposite character using Character.toLowerCase(given input) or Character.toUpperCase(given input).

Program: [This program converts to opposite case – Character]

[java]
package in.javadomain;

public class ChangeToOppositeCharacter {

public static void main(String[] args) {
Character c = ‘d’;
if (Character.isLowerCase(c)) {
System.out.println("Given Case : " + c);
System.out.println("Opposite Case : " + Character.toUpperCase(c));
} else {
System.out.println("Given Case : " + c);
System.out.println("Opposite Case : " + Character.toLowerCase(c));
}
}
}
[/java]

Output:

[plain gutter=”false”]
Given Case : d
Opposite Case : D
[/plain]

 

Program: [Upper case Input, Lower Case Output]

[java]
package in.javadomain;

public class ChangeToOppositeCharacter {

public static void main(String[] args) {
Character c = ‘N’;
if (Character.isLowerCase(c)) {
System.out.println("Given Case : " + c);
System.out.println("Opposite Case : " + Character.toUpperCase(c));
} else {
System.out.println("Given Case : " + c);
System.out.println("Opposite Case : " + Character.toLowerCase(c));
}
}
}
[/java]

Output:

[plain gutter=”false”]
Given Case : N
Opposite Case : n
[/plain]

 

Changing the String Case to Opposite Case: [This program converts to opposite case – String, but returns Character by character]
The above code separated as method and the method called repeatedly.

 

[java]
package in.javadomain;

public class ChangeToOppositeString {

public static void main(String[] args) {
char oppositeChar = 0;
String input = "Javadomain.In";
for (int i = 0; i < input.length(); i++) {
CharSequence val = input.subSequence(i, i + 1);
oppositeChar = oppositeChar(val.charAt(0));
System.out.println(oppositeChar);
}

}

private static char oppositeChar(char c) {
char oppoChar = 0;
if (Character.isLowerCase(c)) {
oppoChar = Character.toUpperCase(c);
} else {
oppoChar = Character.toLowerCase(c);
}
return oppoChar;
}
}
[/java]

Output:

[plain gutter=”false”]
j
A
V
A
D
O
M
A
I
N
.
i
N
[/plain]

 

Printing Opposite Case of a String: [This program converts to opposite case – String]
The above returns the opposite case of a character. If you want the whole word to be returned after the case change, then you can go with the below program.
[java]
package in.javadomain;

public class StringOppositeCase {

public static void main(String[] args) {
String input = "I Love Javadomain.in";
System.out.println("Given Input ::: " + input);
StringBuilder strBuilder = new StringBuilder(input);
for (int i = 0; i < strBuilder.length(); i++) {
char c = strBuilder.charAt(i);
if (Character.isUpperCase(c)) {
strBuilder.setCharAt(i, Character.toLowerCase(c));
} else {
strBuilder.setCharAt(i, Character.toUpperCase(c));
}

}
System.out.println("Opposite Case::: " + strBuilder);

}

}
[/java]

Output:

[plain gutter=”false”]
Given Input ::: I Love Javadomain.in
Opposite Case::: i lOVE jAVADOMAIN.IN
[/plain]

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