java8test.java

package com.company;
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 Main {
    public static void main(String args[]){
        System.out.println("Using Java 7: ");

        // Count empty strings
        List<String> strings = Arrays.asList("abc", "", "bc", "efg", "abcd","", "jkl");
        System.out.println("List: " +strings);
        long count = getCountEmptyStringUsingJava7(strings);

        System.out.println("Empty Strings: " + count);
        count = getCountLength3UsingJava7(strings);

        System.out.println("Strings of length 3: " + count);

        //Eliminate empty string
        List<String> filtered = deleteEmptyStringsUsingJava7(strings);
        System.out.println("Filtered List: " + filtered);

        //Eliminate empty string and join using comma.
        String mergedString = getMergedStringUsingJava7(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("====================================================================================");
        System.out.println("====================================================================================");
        System.out.println("====================================================================================");

        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 getCountEmptyStringUsingJava7(List<String> strings){
        int count = 0;

        for(String string: strings){

            if(string.isEmpty()){
                count++;
            }
        }
        return count;
    }

    private static int getCountLength3UsingJava7(List<String> strings){
        int count = 0;

        for(String string: strings){

            if(string.length() == 3){
                count++;
            }
        }
        return count;
    }

    private static List<String> deleteEmptyStringsUsingJava7(List<String> strings){
        List<String> filteredList = new ArrayList<String>();

        for(String string: strings){

            if(!string.isEmpty()){
                filteredList.add(string);
            }
        }
        return filteredList;
    }

    private static String getMergedStringUsingJava7(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();
    }
}