Java - código de linea que busque palabras terminadas con "ar"

public class HelloWorld

{

  // arguments are passed using the text field below this editor

  public static void main(String[] args)

  {

    String str = "comenzar a programar es dificil pero mas vale empezar ahora que nunca";

    StringBuffer wordsFound = new StringBuffer();

    //wordsFound.append("test");

    //System.out.println("hello");

    StringBuffer word = new StringBuffer();

    for(int i = 0; i < str.length(); i++){

       //System.out.println(str.charAt(i));

      if(str.charAt(i) == ' '){

        //System.out.println(word);

        int lenWord = word.length();

        if(word.length() >= 2){

        //String ar = str.substring(lenWord-2, lenWord);

              if(word.charAt(lenWord-2) == 'a' && word.charAt(lenWord-1) == 'r'){

    		  wordsFound.append(word);

                  wordsFound.append('-');

        	}

        }

          word.setLength(0);

       }else{

      	  word.append(str.charAt(i));

      }

     }

      System.out.println(wordsFound);

  }

}

import java.util.Scanner;

import java.util.regex.Pattern;

import java.util.regex.Matcher;

class Main {

  public static void main(String[] args) {

    System.out.println("Ingrese una cadena: ");

    Scanner sc = new Scanner(System.in);

    String cadena = sc.nextLine();

    Pattern patron = Pattern.compile("\\b(\\w+ar)\\b", Pattern.MULTILINE);

    Matcher matcher = patron.matcher(cadena);

    String encontradas = "";

    while (matcher.find()) encontradas += matcher.group(1) + " ";

    encontradas.trim();

    System.out.println(encontradas);

  }

}

import java.util.Scanner;

import java.util.regex.Pattern;

import java.util.regex.Matcher;

class Main {

  public static void main(String[] args) {

    System.out.println("Ingrese una cadena: ");

    Scanner sc = new Scanner(System.in);

    String cadena = sc.nextLine();

    System.out.println("Desearia buscar las palabras terminadas en: ");

    String termina = sc.nextLine();

    Pattern patron = Pattern.compile("\\b(\\w+"+termina.trim()+")\\b", Pattern.MULTILINE);

    Matcher matcher = patron.matcher(cadena);

    String encontradas = "";

    while (matcher.find()) encontradas += matcher.group(1) + " ";

    encontradas.trim();

    System.out.println(encontradas);

  }

}