Question

Efficiency of Array vs. ArrayList-- Use JAVA to implement the operations

Using the list operations fill, increment, and search, investigate whether arrays or ArrayLists are faster, or whether they are about the same for int and float values. This will also test times to generate both int and float random numbers as well as the time cost of automatic expansion of an ArrayList. Remember: int and float are used in simple arrays, Integer and Float are used in the ArrayList. All results will be written to a single file named P3Output.txt (Hint – open the file for append)

The program has one class. Main calls methods for each of the operations (fill and increment ). The methods each do their own timing and output.  

Input / output

This program has no input. Output goes to the file, you may also wish to display it on the screen for convenience. The numeric values must be formatted and the times must be in the same scale.

Output format as below:

int array – wall clock : xxx.xxxx seconds

int ArrayList – wall clock : xxx.xxxx seconds

int array – CPU time : xxx.xxxx seconds

int ArrayList – CPU time : xxx.xxxx seconds

float array – wall clock : xxx.xxxx seconds

float ArrayList – wall clock : xxx.xxxx seconds

float array – CPU time : xxx.xxxx seconds

float ArrayList – CPU time : xxx.xxxx seconds

Increment elements in the list:

int array – wall clock : xxx.xxxx seconds

int ArrayList – wall clock : xxx.xxxx seconds

int array – CPU time : xxx.xxxx seconds

int ArrayList – CPU time : xxx.xxxx seconds

float array – wall clock : xxx.xxxx seconds

float ArrayList – wall clock : xxx.xxxx seconds

float array – CPU time : xxx.xxxx seconds

float ArrayList – CPU time : xxx.xxxx seconds

Answer 1

import java.util.*;
import java.nio.file.*;
import java.io.*;
import java.text.*;
import java.util.concurrent.TimeUnit;

public class P3Program
{
    Random randomGenerator;
    DecimalFormat formatter = new DecimalFormat("000.000000000");
    String fileName;
    String outputString;
    public static final int COLLECTION_SIZE = 100000;
    public static final int RANDOM_MAX = 10000000;
    public static final String LS = System.lineSeparator();
    static int trials;

    ArrayList<Float> floatList;
    ArrayList<Integer> intList;
    int intArray[];
    float floatArray[];

    double startCPUTime;
    double stopCPUTime;
    double startWallClockTime;
    double stopWallClockTime;

    /**
     * Instantiate all the data structures we'll be testing.
     */
    public P3Program(){
        intArray = new int[COLLECTION_SIZE];
        floatArray = new float[COLLECTION_SIZE];
        floatList = new ArrayList(COLLECTION_SIZE);
        intList = new ArrayList(COLLECTION_SIZE);
        randomGenerator = new Random();
        fileName = "P3Output.txt";
        trials = 0;
    }

    /**
     * Fills both the ArrayList and the array with values.
     */
    private void fill(){
        System.out.println("++++++++FILL+++++++");
        startWallClockTime = System.currentTimeMillis();
        startCPUTime = System.nanoTime();
        for(int i = 0; i < intArray.length; i++){
            intArray[i] = randomGenerator.nextInt(RANDOM_MAX);
        }
        stopWallClockTime = System.currentTimeMillis();
        stopCPUTime = System.nanoTime();
        double intArrayWallTime = stopWallClockTime - startWallClockTime;
        double intArrayCPUTime = stopCPUTime - startCPUTime;

        startWallClockTime = System.currentTimeMillis();
        startCPUTime = System.nanoTime();
        for(int i = 0; i < floatArray.length; i++){
            floatArray[i] = randomGenerator.nextFloat();
        }
        stopWallClockTime = System.currentTimeMillis();
        stopCPUTime = System.nanoTime();
        double floatArrayWallTime = stopWallClockTime - startWallClockTime;
        double floatArrayCPUTime = stopCPUTime - startCPUTime;

        startWallClockTime = System.currentTimeMillis();
        startCPUTime = System.nanoTime();
        for(int i = 0; i < COLLECTION_SIZE; i++){
            intList.add(i, randomGenerator.nextInt(RANDOM_MAX));
        }
        stopWallClockTime = System.currentTimeMillis();
        stopCPUTime = System.nanoTime();
        double intListWallTime = stopWallClockTime - startWallClockTime;
        double intListCPUTime = stopCPUTime - startCPUTime;

        startWallClockTime = System.currentTimeMillis();
        startCPUTime = System.nanoTime();
        for(int i = 0; i < COLLECTION_SIZE; i++){
            floatList.add(i, randomGenerator.nextFloat());
        }
        stopWallClockTime = System.currentTimeMillis();
        stopCPUTime = System.nanoTime();
        double floatListWallTime = stopWallClockTime - startWallClockTime;
        double floatListCPUTime = stopCPUTime - startCPUTime;

        outputString = "Run # " + trials + LS + "Fill the list: Number of Elements: " + COLLECTION_SIZE +
                LS + "   int array - wall clock          : " + formatter.format(intArrayWallTime/1000) +
                LS + "   int ArrayList - wall clock      : " + formatter.format(intListWallTime/1000) +
                LS + LS + "   int array - CPU time            : " + formatter.format(intArrayCPUTime/1000000000) +
                LS + "   int ArrayList - CPU time        : " + formatter.format(intListCPUTime/1000000000) +
                LS + LS + "   float array - wall clock        : " + formatter.format(floatArrayWallTime/1000) +
                LS + "   float ArrayList - wall clock    : " + formatter.format(floatListWallTime/1000) +
                LS + LS + "   float array - CPU time          : " + formatter.format(floatArrayCPUTime/1000000000) +
                LS + "   float ArrayList - CPU time      : " + formatter.format(floatListCPUTime/1000000000) + LS + LS;
        System.out.println(outputString);
        writeReport(outputString);
    }

    /**
     * Increments every element in each data structure by 1.
     */
    private void increment(){
        System.out.println("++++++INCREMENT+++++++");
        startWallClockTime = System.currentTimeMillis();
        startCPUTime = System.nanoTime();
        for(int i = 0; i < intArray.length; i++){
            intArray[i]++;
        }
        stopWallClockTime = System.currentTimeMillis();
        stopCPUTime = System.nanoTime();
        double intArrayWallTime = stopWallClockTime - startWallClockTime;
        double intArrayCPUTime = stopCPUTime - startCPUTime;

        startWallClockTime = System.currentTimeMillis();
        startCPUTime = System.nanoTime();
        for(int i = 0; i < floatArray.length; i++){
            floatArray[i]++;
        }
        stopWallClockTime = System.currentTimeMillis();
        stopCPUTime = System.nanoTime();
        double floatArrayWallTime = stopWallClockTime - startWallClockTime;
        double floatArrayCPUTime = stopCPUTime - startCPUTime;

        startWallClockTime = System.currentTimeMillis();
        startCPUTime = System.nanoTime();
        for(int i = 0; i < COLLECTION_SIZE; i++){
            int incremented = intList.get(i) + 1;
            intList.set(i, incremented);
        }
        stopWallClockTime = System.currentTimeMillis();
        stopCPUTime = System.nanoTime();
        double intListWallTime = stopWallClockTime - startWallClockTime;
        double intListCPUTime = stopCPUTime - startCPUTime;

        startWallClockTime = System.currentTimeMillis();
        startCPUTime = System.nanoTime();
        for(int i = 0; i < COLLECTION_SIZE; i++){
            float incremented = floatList.get(i) + 1;
            floatList.set(i, incremented);
        }
        stopWallClockTime = System.currentTimeMillis();
        stopCPUTime = System.nanoTime();
        double floatListWallTime = stopWallClockTime - startWallClockTime;
        double floatListCPUTime = stopCPUTime - startCPUTime;

        outputString = "Increment the elements in the list: " +
                LS + "   int array - wall clock          : " + formatter.format(intArrayWallTime/1000) +
                LS + "   int ArrayList - wall clock      : " + formatter.format(intListWallTime/1000) +
                LS + LS + "   int array - CPU time            : " + formatter.format(intArrayCPUTime/1000000000) +
                LS + "   int ArrayList - CPU time        : " + formatter.format(intListCPUTime/1000000000) +
                LS + LS + "   float array - wall clock        : " + formatter.format(floatArrayWallTime/1000) +
                LS + "   float ArrayList - wall clock    : " + formatter.format(floatListWallTime/1000) +
                LS + LS + "   float array - CPU time          : " + formatter.format(floatArrayCPUTime/1000000000) +
                LS + "   float ArrayList - CPU time      : " + formatter.format(floatListCPUTime/1000000000) + LS + LS;
        System.out.println(outputString);
        writeReport(outputString);
        intList.clear();
        floatList.clear();
    }

    /**
     * Writes the report with the data from the trial
     */
    private void writeReport(String reportString){
        try{
            BufferedWriter writer = new BufferedWriter(new FileWriter(new File(fileName), true));
            writer.write(reportString);
            writer.close();
        }catch(Exception ex){
            System.out.println("try a different file name");
        }
    }

    /**
     * The main method that calls all the methods from the class.
     */
    public static void main(String args[]){
        P3Program arrayTest = new P3Program();
        while(trials <= 3){
            trials++;
            arrayTest.fill();
            arrayTest.increment();
        }
    }

}

P3Program - [CAUsers SwapninP3Program] - P3Program.java - Intelli IDEA 2017.2.5 Eile Edit View Navigate Code Analyze Rcfactor Build Run Iools VCS Window Help P3Program SrcP3Program Run o Main "C:\Program Files\Java\jdk1.е.0-92\bin\java Fill the liat: Nunber of Elements: 100000 int array - wall clock nt ArrayL1at - wal1 clock : 000.016000000 :000.015000000 咀帚 int array -CPU tine int ArrayList-CPU tine : 000.011340582 : 000.018733155 float array wall clock float ArravList-Wall clock : 000.016000000 : 000.000000000 loat array -CPU time float Arrayist- CPT time : 000.012214449 : 000.008930714 Increnent the elenents in the list: int array - wall clock nt ArrayL1at - wal1 clock : 000.015000000 :000.032000000 int array -CPU tine int ArrayList-CPU tine : 000.004674734 : 000.025147067 float array wall clock float ArravList-Wall clock : 000.000000000 : 000.000000000 loat array CPU time float Arraylist- CPT time : 000.003043774 : 000.007772831 Activate Windows Run # Terminal Q MessagesRun&TODO Compilation c Event Log leted successfully in 10s 24ms 15:56 LF UTF-8