CC-7 : Reverse the characters of the input String.

Description:

Given input String str, reverse its characters and return the reversed string.

Test cases and expected outputs:

Input Parameters	Expected outputs
str1="Reverse"	esreveR
str1="Java is the best!";	!tseb eht si avaJ

Pseudocode:

The java method should accept following input parameters: str (String).

Initialize integer variable left to 0. Initialize integer variable right to str.length()-1.

Extract the characters from str into char array names chars.

Initialize char variable temp to false. We will use temp to swap characters while reversing the characters of str.

Iterate through chars using while loop while left < right:

Swap characters at chars[left] and chars[right].

Increment left by 1.

Decrement right by 1.

After above loop has completed, chars contains the characters of str in reverse order. Create a String from chars and return the newly created String with reversed characters.

Code:

public String stringReverse(String str) {
	int left=0; int right=str.length()-1;
	char[] chars=str.toCharArray();
	char temp;
	while (left < right) {
		temp=chars[left];
		chars[left]=chars[right];
		chars[right]=temp;
		left++;
		right--;		
	}
	return new String(chars);
}

Click here to download and run code and test cases !

Below fully running code can be copied and run on Eclipse or other Java IDEs. Refer the classname in code below. If the class name below is "A", save the code below to a file named A.java before running it. Be sure to try your own test cases to enhance your understanding ! You can also tweak the code to optimize or add enhancements and custom features.

public class StringReverse {
	
public String stringReverse(String str) {
	int left=0; int right=str.length()-1;
	char[] chars=str.toCharArray();
	char temp;
	while (left < right) {
		temp=chars[left];
		chars[left]=chars[right];
		chars[right]=temp;
		left++;
		right--;		
	}
	return new String(chars);
}
	
public static void main(String[] args) {
	StringReverse sp=new StringReverse();
	String retStr;
		
	try {
	String str1="Reverse";
	System.out.println("\n\nThe original string is: "+str1);
	retStr=sp.stringReverse(str1);
	System.out.println("The reversed string is: "+retStr);
			
	str1="Java is the best!";
	System.out.println("\n\nThe original string is: "+str1);
	retStr=sp.stringReverse(str1);
	System.out.println("The reversed string is: "+retStr);
			
			
	}catch (Exception exception) {
	System.out.print("Exception,"+ exception);
	exception.printStackTrace();
				
	}
}

}