Prime Numbers Finder Example

src/main/java/PrimeFinder.java

+import java.util.ArrayList;
+import java.util.List;
+
+public class PrimeFinder {
+    private int start;
+    private int end;
+    private List<Integer> primes;
+
+    public PrimeFinder(int start, int end)
+    {
+        this.start = start;
+        this.end = end;
+        this.primes = new ArrayList<>();
+    }
+
+    public List<Integer> getPrimes()
+    {
+        for (int i= this.start  ; i <= this.end ; i++)
+        {
+            boolean isPrime = true;
+            for (int j=2 ; j <= Math.sqrt(i); j++)
+            {
+                if (i%j == 0)
+                {
+                    isPrime  = false;
+                    break;
+                }
+            }
+            if (isPrime)
+            {
+                primes.add(i);
+            }
+        }
+        return this.primes;
+    }
+
+
+
+
+}

src/test/java/PrimeNumTest.java

+import junit.framework.TestCase;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class PrimeNumTest extends TestCase {
+
+    public void testFindPrimesSeq()
+    {
+        PrimeFinder primeFinder = new PrimeFinder(1, 100_000_000);
+        long startTime = System.currentTimeMillis();
+        List<Integer> Primes1 = primeFinder.getPrimes();
+        long end = System.currentTimeMillis() -startTime;
+
+        System.out.println("Time Taken = " + end);
+        System.out.println(Primes1.size());
+
+        assertEquals(5761456, Primes1.size());
+    }
+
+    public void testChunksRange(){
+            int[] rangeLength = {100_000_000, 10_000_000, 1_000_000};
+            int[] NumThreads = {1,2,3,4,5,6,7,8,9,10,20,30,40};
+
+            for(int rl: rangeLength){
+                for(int nt : NumThreads){
+                    System.out.printf("Range Length: %-9d, NumThread: %d \n",rl,nt);
+
+                    List<Thread> primeTh = new ArrayList<>();
+                    for (int n = 0; n < nt; ++n) {
+                        int start = getChunkStart(n, nt, rl);
+                        int end = getChunkEnd(n, nt, rl);
+                        System.out.println(start+ " "+ end);
+                    }
+                }
+            }
+        }
+
+    public void testFindPrimesThread(){
+        int[] rangeLength = {100_000_000, 10_000_000, 1_000_000};
+        int[] NumThreads = {1,2,3,4,5,6,7,8,9,10,20,40,100,200,500,1000};
+
+        for(int rl: rangeLength){
+            for(int nt : NumThreads){
+                System.out.printf("Range Length: %-9d, NumThread: %d \n",rl,nt);
+
+                List<Thread> primeTh = new ArrayList<>();
+                for (int n = 0; n < nt; ++n) {
+                    int start = getChunkStart(n, nt, rl);
+                    int end = getChunkEnd(n, nt, rl);
+                    PrimeFinder primeFinder = new PrimeFinder(start, end);
+                    Thread th = new Thread(() -> primeFinder.getPrimes());
+                    primeTh.add(th);
+                }
+
+                long StartTime= System.currentTimeMillis();
+
+                for(Thread primeFinderTh : primeTh){
+                    primeFinderTh.start();
+                }
+
+                for(Thread primeFinderTh : primeTh){
+                    try {
+                        primeFinderTh.join();
+                    } catch (InterruptedException e) {
+                        throw new RuntimeException(e);
+                    }
+                }
+                long end = System.currentTimeMillis()- StartTime;
+                System.out.println("Time Taken: "+ end);
+
+            }
+        }
+    }
+
+    private static int getChunkSize(final int nChunks, final int nElements) {
+        return (nElements + nChunks - 1) / nChunks;
+    }
+
+    private static int getChunkStart(final int chunk,
+                                              final int nChunks, final int nElements) {
+        final int chunkSize = getChunkSize(nChunks, nElements);
+        return (chunk * chunkSize)+1;
+    }
+    private static int getChunkEnd(final int chunk, final int nChunks,
+                                            final int nElements) {
+        final int chunkSize = getChunkSize(nChunks, nElements);
+        final int end = (chunk + 1)  * chunkSize;
+        if (end > nElements) {
+            return nElements;
+        } else {
+            return end;
+        }
+    }
+
+
+}

src/test/java/StudentServiceTest.java

 import junit.framework.TestCase;
-
 import java.util.ArrayList;
 import java.util.List;