Reverse the Order of the Words in a Sentence in Java Example

Stack-This class is a predefined class of java.uti1package. A stack represents a group of elements stored in LIFO (Last In Fast Out) order. This means that the element stored as a last element in the stack will be the first element to be removed from the stack.

Methods of Stack class:

1. bolean empty(): It checks whether the stack is empty or not. If the stack is empty it returns true.

2. element peek():This method returns the top most object from the stack without removing it.

3. element pop():This method remove the top most element from the stack and returns the element.

4. element push(element object): This method insert an element object into the top of the stack and returns that element.

StringTokenizer: This class is a predefined class present in java.util package.It used to break the String into pieces i.e.tokens. These tokens are stored in StringTokenizer object from which they can be retrieved.

Methods:

1. boolean has MoreToken():- It used to test if there are more tokens available in the String Tokenizer object or not. It returns true if next token is present.

2. String nextTokens():- This method returns the next tokens from the StringTokenizer.

3. int countTokens():- It returns the number of tokens present in StringTokenizer object.

Algorithm for Reverse the Order of the Words in a Sentence:

step 1: read String a

step 2: create object of Stack class named sta

step 3: StringTokenizer st= new StringTokenizer(a)

step 4: repeat through step-5 while (st.hasMoreTokens()) returns true

step 5: sta.push( st. nextElement())

step 6: repeat through step-5 while(sta.empty()) returns false

step 7: print sta.pop()

step 8: print one space

step 9: Exit

Here is the Java Example for Reverse the Order of the Words in a Sentence:

import java.util.*; 
 public class ReverseOrderWords  
 { 
                public static void main(String[] args) 
          { 
                      System.out.print("Enter a Sentence : "); 
                      Scanner s=new Scanner(System.in); 
                      String a=s.nextLine(); 
                      Stack sta=new Stack(); 
                      StringTokenizer st=new StringTokenizer(a); 
                            while(st.hasMoreTokens()) 
                                    { 
                                        sta.push(st.nextElement()); 
                                    } 
                                        System.out.println("\nOriginal string : " + a); 
                                        System.out.print("Reverse Order Words : "); 
                                              while(!sta.empty()) 
                                                      { 
                                                          System.out.print(sta.pop()); 
                                                          System.out.print(" "); 
                                                      } 
                                                           
             }                       
 }