Stream03.java

package August;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.IntSummaryStatistics;
import java.util.List;
import java.util.Random;
import java.util.stream.Collectors;
import java.util.Map;

public class Stream03 {

	public static void main(String[] args) {
		 // Count empty strings
	      List<String> strings = Arrays.asList("abc", "", "bc", "efg", "abcd","", "jkl");
	      System.out.println("List: " +strings);
	      long count = getCountEmpty(strings);
			
	      System.out.println("Empty Strings: " + count);
	      count = getCountLength(strings);
			
	      System.out.println("Strings of length 3: " + count);
			
	      //Eliminate empty string
	      List<String> filtered = deleteEmptyStrings(strings);
	      System.out.println("Filtered List: " + filtered);
			
	      //Eliminate empty string and join using comma.
	      String mergedString = getMergedString(strings,", ");
	      System.out.println("Merged String: " + mergedString);
	      List<Integer> numbers = Arrays.asList(3, 2, 2, 3, 7, 3, 5);
			
	      //get list of square of distinct numbers
	      List<Integer> squaresList = getSquares(numbers);
	      System.out.println("Squares List: " + squaresList);
	      List<Integer> integers = Arrays.asList(1,2,13,4,15,6,17,8,19);
			
	      System.out.println("List: " +integers);
	      System.out.println("Highest number in List : " + getMax(integers));
	      System.out.println("Lowest number in List : " + getMin(integers));
	      System.out.println("Sum of all numbers : " + getSum(integers));
	      System.out.println("Average of all numbers : " + getAverage(integers));
	      System.out.println("Random Numbers: ");
			
	      //print ten random numbers
	      Random random = new Random();
			
	      for(int i = 0; i < 10; i++) {
	         System.out.println(random.nextInt());
	      }
			
	      System.out.println("Using Java 8: ");
	      System.out.println("List: " +strings);
			
	      count = strings.stream().filter(string->string.isEmpty()).count();
	      System.out.println("Empty Strings: " + count);
			
	      count = strings.stream().filter(string -> string.length() == 3).count();
	      System.out.println("Strings of length 3: " + count);
			
	      filtered = strings.stream().filter(string ->!string.isEmpty()).collect(Collectors.toList());
	      System.out.println("Filtered List: " + filtered);
			
	      mergedString = strings.stream().filter(string ->!string.isEmpty()).collect(Collectors.joining(", "));
	      System.out.println("Merged String: " + mergedString);
			
	      squaresList = numbers.stream().map( i ->i*i).distinct().collect(Collectors.toList());
	      System.out.println("Squares List: " + squaresList);
	      System.out.println("List: " +integers);
			
	      IntSummaryStatistics stats = integers.stream().mapToInt((x) ->x).summaryStatistics();
			
	      System.out.println("Highest number in List : " + stats.getMax());
	      System.out.println("Lowest number in List : " + stats.getMin());
	      System.out.println("Sum of all numbers : " + stats.getSum());
	      System.out.println("Average of all numbers : " + stats.getAverage());
	      System.out.println("Random Numbers: ");
			
	      random.ints().limit(10).sorted().forEach(System.out::println);
			
	      //parallel processing
	      count = strings.parallelStream().filter(string -> string.isEmpty()).count();
	      System.out.println("Empty Strings: " + count);
	   }
		
	   private static int getCountEmpty(List<String> strings) {
	      int count = 0;

	      for(String string: strings) {
			
	         if(string.isEmpty()) {
	            count++;
	         }
	      }
	      return count;
	   }
		
	   private static int getCountLength(List<String> strings) {
	      int count = 0;
			
	      for(String string: strings) {
			
	         if(string.length() == 3) {
	            count++;
	         }
	      }
	      return count;
	   }
		
	   private static List<String> deleteEmptyStrings(List<String> strings) {
	      List<String> filteredList = new ArrayList<String>();
			
	      for(String string: strings) {
			
	         if(!string.isEmpty()) {
	             filteredList.add(string);
	         }
	      }
	      return filteredList;
	   }
		
	   private static String getMergedString(List<String> strings, String separator) {
	      StringBuilder stringBuilder = new StringBuilder();
			
	      for(String string: strings) {
			
	         if(!string.isEmpty()) {
	            stringBuilder.append(string);
	            stringBuilder.append(separator);
	         }
	      }
	      String mergedString = stringBuilder.toString();
	      return mergedString.substring(0, mergedString.length()-2);
	   }
		
	   private static List<Integer> getSquares(List<Integer> numbers) {
	      List<Integer> squaresList = new ArrayList<Integer>();
			
	      for(Integer number: numbers) {
	         Integer square = new Integer(number.intValue() * number.intValue());
				
	         if(!squaresList.contains(square)) {
	            squaresList.add(square);
	         }
	      }
	      return squaresList;
	   }
		
	   private static int getMax(List<Integer> numbers) {
	      int max = numbers.get(0);
			
	      for(int i = 1;i < numbers.size();i++) {
			
	         Integer number = numbers.get(i);
				
	         if(number.intValue() > max) {
	            max = number.intValue();
	         }
	      }
	      return max;
	   }
		
	   private static int getMin(List<Integer> numbers) {
	      int min = numbers.get(0);
			
	      for(int i= 1;i < numbers.size();i++) {
	         Integer number = numbers.get(i);
			
	         if(number.intValue() < min) {
	            min = number.intValue();
	         }
	      }
	      return min;
	   }
		
	   private static int getSum(List numbers) {
	      int sum = (int)(numbers.get(0));
			
	      for(int i = 1;i < numbers.size();i++) {
	         sum += (int)numbers.get(i);
	      }
	      return sum;
	   }
		
	   private static int getAverage(List<Integer> numbers) {
	      return getSum(numbers) / numbers.size();
	   }
	

	

}