Reverse string in java means that swap first character with last and second character with second last and so on . In this post , we will discuss different methods for write java program to reverse a string as following .
- Reverse a string in java using for loop
- Reverse a string in java using While loop
- Reverse a string in java using Recursion
- Reverse a string in java using array
- Reverse a string in java using String Buffer
Reverse a String in java using for loop
In this method , we see how to reverse a string in java using for loop . We will follow these steps for reverse a string in java using for loop .
- Declare a string str .
- Take a empty string reverse , which is our final output as reverse string.
- Iterate str in reverse order till i >= 0 and each iterate append char at the end of reverse string with the help of charAt() method.
public class ReverseStringUsingForloop {
public static void main(String[] args) {
String str = "javavogue";
String reverse = "";
for (int i = str.length()-1; i >= 0 ; i--) {
reverse = reverse + str.charAt(i);
}
System.out.println("reverse string is :"+ reverse);
}
}
Output :
reverse string is :eugovavaj
We have reverse a string in java using for loop. we can reverse a sentence in java or reverse a word in java using same approach . Now we will write a java program to reverse a string using while loop .
Reverse a string in java using While loop
In this method we will use while loop instead of for loop in above approach . In this example we will reverse a string in java without using inbuilt function .
public class ReverseStringUsingWhile {
public static void main(String[] args) {
String str = "javavogue";
String reverse = "";
int i = str.length()-1;
while(i >= 0 ) {
reverse = reverse + str.charAt(i);
i--;
}
System.out.println("reverse string is :"+ reverse);
}
}
Output :
reverse string is :eugovavaj
We have seen java code to reverse a string using while loop .we can reverse sentence in java without using split using this example also . Now we will see java how to reverse a string using recursion .
Reverse a string in java using Recursion
We will write a program for reverse a string in java using recursion. we use base case till string length is = 1
public class ReverseStringUsingRecursion {
public static void main(String[] args) {
String str = "javavogue";
System.out.println("reverse string is =" + recursiveReverse(str));
}
public static String recursiveReverse(String str) {
if (str.length() == 1)
return str;
else
return str.charAt(str.length() - 1)
+ recursiveReverse(str.substring(0, str.length() - 1));
}
}
Output :
reverse string is =eugovavaj
In this example we have used substring() method of string for reverse a string .
Reverse a string in java using array
In this method we will create array from string using toArray() method of string . Now We Iterate this char array in reverse order and each iteration append char from char array to reverse string. we can reverse char array java using same approach .
public class ReverseStringUsingArray {
public static void main(String[] args) {
String str = "javavogue";
String reverse = "";
char arr [] = str.toCharArray();
int i = arr.length -1;
while(i >= 0 ) {
reverse = reverse + arr[i] ;
i--;
}
System.out.println("reverse string is :"+ reverse);
}
}
Output :
reverse string is =eugovavaj
Reverse a string in java using String Buffer
In this example we see how to reverse string in java using string buffer’s reverse method .
public class ReverseStringUsingStringBuffer {
public static void main(String[] args) {
String str = "javavogue";
StringBuffer buffer = new StringBuffer(str);
System.out.println("reverse string is ="+ buffer.reverse());
}
}
Output :
reverse string is =eugovavaj
You can see top coding interview question and top string program for interview .