How to print every other word(not single character) in a sentence/string in Java?

Question

I want to print every other word in a sentence/string. And in the output, first letter should be in upper case.
Example:

Enter a string: Hello how are you doing today?
The resulting string is: 
How you today?

This is the code I have tried. It is working fine but I wanted to improve the code. Please let me know what are the improvements that can be made in the code. I have not worked with StringBuilder much. So, I wanted to write the code using it or if I can write the code using different functions.
Thanks in advance.

import java.util.*; 
 
public class Main{

    public String skipWords(String str){
        String a ="";
            String[] wordsArr = str.split(" ");
            for(int i = 0 ; i< wordsArr.length; i++){
                if(i%2 != 0) 
                        a= a+wordsArr[i] + " ";
                    else 
                        a = a.replace(wordsArr[i]," ");
            }
        return a; 
    }

    public String fCapital(String str){
            String f = str.substring(0, 1);
            String r = str.substring(1);
            f = f.toUpperCase();
            String c = f + r;
            return c;
    }

    public static void main(String[] args){
            String result = "";
            Main obj = new Main();
            Scanner sc= new Scanner(System.in); 
            System.out.print("Enter a string: ");  
            String str= sc.nextLine();      
            String w = obj.skipWords(str);
            result = obj.fCapital(w);   
            System.out.println("The resulting string is: ");
            System.out.println(result);   
    }
}

Answer 1

Take a look:

public String skipWords(String sentence) {
    String[] words = sentence.split(" ");
    StringBuilder result = new StringBuilder();

    for (int i = 1; i < words.length + 1; i += 2) {
        result.append(words[i]).append(" ");
    }
    return result.toString();
}

• Meaningful variable names.
• StringBuilder instead of + operator.

Answer 2

I think you can try this below one and reduce so many lines and also calling the static methods which costs a lot

String str = sc.nextLine();
String removefirst = (str.split(" ",2)[1]);
String finalVal = removefirst.substring(0, 1).toUpperCase() + removefirst.substring(1);

and the output will look like this,

Enter a string: league of legends
Of legends

in the removeFirst variable will take the String with first word removed and then in the finalVal variable will contain the string with first letter capital, if you want to reduce variables as well you can merge those two in to one and use it.

Answer 3

One improvement you can make in your code is to remove this line:

                else 
                    a = a.replace(wordsArr[i]," ");

It serves no real purpose, and can actually lead to wrong results by erasing a skipped word which also happens to be a non skipped word that was added previouisly. For example the input "abc abc abc abc abc" will be reduced to nothing.

The points raised by the other answers such as meaningful names and using StringBuilder to build strings more efficiently are also valid.

Finally, as an alternative you can also use Streaming APIs, this example requires Java 9.

public String skipWords(String str){
     String[] list = str.split(" ");
     String result = Stream.iterate(1, i->i+2).takeWhile(i-> i<list.length).map(i->list[i]).collect(Collectors.joining( " " ));
     return result;
}

It splits the String into an array, then uses Stream.iterate to build a stream of the numbers 1,3,5,7,... etc and then uses takeWhile to limit that stream to the length of the array. The map function takes each other word e.g. by turning 1 into list[1], and the collect function joins them all into one string.

With Java 11, the iteration can be shortened to

     String result = Stream.iterate(1, i->i<list.length,i->i+2).map(i->list[i]).collect(Collectors.joining( " " ));