Easy way to reverse String

Question

Without going through the char sequence is there any way to reverse String in Java

Answer 1

You may use StringBuilder..

String word = "Hello World!";
StringBuilder sb = new StringBuilder(word);

System.out.print(sb.reverse());

Answer 2

Use StringBuilder's or StringBuffer's method... reverse()

 public class StringReverse
{
  public static void main(String[] args)
  {
  String string=args[0];
  String reverse = new StringBuffer(string).reverse().toString();
  System.out.println("\nString before reverse: "+string);
  System.out.println("String after reverse: "+reverse);
  } 
} 

StringBuffer is thread-safe, where as StringBuilder is Not thread safe..... StringBuilder was introduced from Java 1.5, as to do those operations faster which doesn't have any Concurrency to worry about....

Answer 3

Try reverse() method:

StringBuilder stringName = new StringBuilder();
String reverse = stringName.reverse().toString();

Answer 4

Using minimal API support. A simple algorithm.

static String reverse(String str) {
    char[] buffer = str.toCharArray();
    for (int i = 0; i < buffer.length/2; ++i){
        char c = buffer[i];
        buffer[i] = buffer[buffer.length-1-i];
        buffer[buffer.length-1-i] = c;
    }
    return new String(buffer);
}

Answer 5

If we have to do it:

Without going through the char sequence

One easy way with iteration will be:

public String reverse(String post) {                
    String backward = "";
    for(int i = post.length() - 1; i >= 0; i--) {
        backward += post.substring(i, i + 1);
    }        
    return backward;
} 

Answer 6

Here I have a sample of the same using substring method and o(n) without using any nethods from string . I am aware that using substring will hold complete string memory.

for(int i = 0; i < s.length(); i++)    {
    s = s.substring(1, s.length() - i) + s.charAt(0) + s.substring(s.length() - i);
    System.out.println(s);
}

This might help you!!