[BAEL-3211] Generate Integers within a range in Java (eugenp#7668)

harshavs · maibin · commit bfd84477ee18 · 2019-08-28T21:46:47.000-07:00
* [BAEL-3211] Generate Integers within a range in Java

* [BAEL-3211] Generate Integers within a range in Java

* Moved files from java-numbers to java-numbers-2
diff --git a/java-numbers-2/src/main/java/com/baeldung/numbersinrange/NumbersInARange.java b/java-numbers-2/src/main/java/com/baeldung/numbersinrange/NumbersInARange.java
@@ -0,0 +1,36 @@
+package com.baeldung.numbersinrange;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class NumbersInARange {
+
+    public List<Integer> getNumbersInRange(int start, int end) {
+        List<Integer> result = new ArrayList<>();
+        for (int i = start; i < end; i++) {
+            result.add(i);
+        }
+        return result;
+    }
+
+    public List<Integer> getNumbersUsingIntStreamRange(int start, int end) {
+        return IntStream.range(start, end)
+          .boxed()
+          .collect(Collectors.toList());
+    }
+
+    public List<Integer> getNumbersUsingIntStreamRangeClosed(int start, int end) {
+        return IntStream.rangeClosed(start, end)
+          .boxed()
+          .collect(Collectors.toList());
+    }
+
+    public List<Integer> getNumbersUsingIntStreamIterate(int start, int limit) {
+        return IntStream.iterate(start, i -> i + 1)
+          .limit(limit)
+          .boxed()
+          .collect(Collectors.toList());
+    }
+}
diff --git a/java-numbers-2/src/main/java/com/baeldung/numbersinrange/RandomNumbersInARange.java b/java-numbers-2/src/main/java/com/baeldung/numbersinrange/RandomNumbersInARange.java
@@ -0,0 +1,22 @@
+package com.baeldung.numbersinrange;
+
+import java.util.Random;
+
+public class RandomNumbersInARange {
+
+    public int getRandomNumber(int min, int max) {
+        return (int) ((Math.random() * (max - min)) + min);
+    }
+
+    public int getRandomNumberUsingNextInt(int min, int max) {
+        Random random = new Random();
+        return random.nextInt(max - min) + min;
+    }
+
+    public int getRandomNumberUsingInts(int min, int max) {
+        Random random = new Random();
+        return random.ints(min, max)
+          .findFirst()
+          .getAsInt();
+    }
+}
diff --git a/java-numbers-2/src/test/java/com/baeldung/numbersinrange/NumbersInARangeUnitTest.java b/java-numbers-2/src/test/java/com/baeldung/numbersinrange/NumbersInARangeUnitTest.java
@@ -0,0 +1,43 @@
+package com.baeldung.numbersinrange;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Test;
+
+public class NumbersInARangeUnitTest {
+
+    @Test
+    public void givenTheRange1To10_andUsingForLoop_thenExpectCorrectResult() {
+        NumbersInARange numbersInARange = new NumbersInARange();
+        List<Integer> numbers = numbersInARange.getNumbersInRange(1, 10);
+        
+        assertEquals(Arrays.asList(1,2,3,4,5,6,7,8,9), numbers);
+    }
+    
+    @Test
+    public void givenTheRange1To10_andUsingIntStreamRange_thenExpectCorrectResult() {
+        NumbersInARange numbersInARange = new NumbersInARange();
+        List<Integer> numbers = numbersInARange.getNumbersUsingIntStreamRange(1, 10);
+        
+        assertEquals(Arrays.asList(1,2,3,4,5,6,7,8,9), numbers);
+    }
+    
+    @Test
+    public void givenTheRange1To10_andUsingIntStreamRangeClosed_thenExpectCorrectResult() {
+        NumbersInARange numbersInARange = new NumbersInARange();
+        List<Integer> numbers = numbersInARange.getNumbersUsingIntStreamRangeClosed(1, 10);
+        
+        assertEquals(Arrays.asList(1,2,3,4,5,6,7,8,9,10), numbers);
+    }
+    
+    @Test
+    public void givenTheRange1To10_andUsingIntStreamIterate_thenExpectCorrectResult() {
+        NumbersInARange numbersInARange = new NumbersInARange();
+        List<Integer> numbers = numbersInARange.getNumbersUsingIntStreamIterate(1, 10);
+        
+        assertEquals(Arrays.asList(1,2,3,4,5,6,7,8,9,10), numbers);
+    }
+}
diff --git a/java-numbers-2/src/test/java/com/baeldung/numbersinrange/RandomNumbersInARangeUnitTest.java b/java-numbers-2/src/test/java/com/baeldung/numbersinrange/RandomNumbersInARangeUnitTest.java
@@ -0,0 +1,35 @@
+package com.baeldung.numbersinrange;
+
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+public class RandomNumbersInARangeUnitTest {
+
+    @Test
+    public void givenTheRange1To10_andUsingMathRandom_thenExpectCorrectResult() {
+        RandomNumbersInARange randomNumbersInARange = new RandomNumbersInARange();
+        int number = randomNumbersInARange.getRandomNumber(1, 10);
+
+        assertTrue(number >= 1);
+        assertTrue(number < 10);
+    }
+
+    @Test
+    public void givenTheRange1To10_andUsingRandomInts_thenExpectCorrectResult() {
+        RandomNumbersInARange randomNumbersInARange = new RandomNumbersInARange();
+        int number = randomNumbersInARange.getRandomNumberUsingInts(1, 10);
+
+        assertTrue(number >= 1);
+        assertTrue(number < 10);
+    }
+
+    @Test
+    public void givenTheRange1To10_andUsingRandomNextInt_thenExpectCorrectResult() {
+        RandomNumbersInARange randomNumbersInARange = new RandomNumbersInARange();
+        int number = randomNumbersInARange.getRandomNumberUsingNextInt(1, 10);
+
+        assertTrue(number >= 1);
+        assertTrue(number < 10);
+    }
+}
