[array-nullorempty] check array null or empty

Author: sk1418

core-java-modules/core-java-arrays-operations-basic-2/src/test/java/com/baeldung/array/nullorempty/CheckArrayNullOrEmptyUnitTest.java

@@ -0,0 +1,59 @@
+package com.baeldung.array.nullorempty;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.math.BigDecimal;
+
+import org.apache.commons.lang3.ArrayUtils;
+import org.junit.jupiter.api.Test;
+
+public class CheckArrayNullOrEmptyUnitTest {
+
+    private final static String[] STR_ARRAY = new String[] { "a", "b", "c", "d" };
+    private final static BigDecimal[] EMPTY_ARRAY = new BigDecimal[] {};
+    private final static String[] NULL_ARRAY = null;
+    // primitive array
+    private final static int[] INT_ARRAY = new int[] { 1, 2, 3, 4 };
+
+    public static <T> boolean isArrayNullOrEmpty(T[] theArray) {
+        return theArray == null || theArray.length == 0;
+    }
+
+    public static boolean isArrayNullOrEmpty2(Object[] theArray) {
+        return theArray == null || theArray.length == 0;
+    }
+
+    public static boolean isArrayNullOrEmpty(int[] theArray) {
+        return theArray == null || theArray.length == 0;
+    }
+
+    @Test
+    void whenUsingIsArrayNullOrEmpty_thenCorrect() {
+        assertTrue(isArrayNullOrEmpty(NULL_ARRAY));
+        assertTrue(isArrayNullOrEmpty(EMPTY_ARRAY));
+        assertFalse(isArrayNullOrEmpty(STR_ARRAY));
+
+        //int array uses isArrayNullOrEmpty(int[] theArray)
+        assertFalse(isArrayNullOrEmpty(INT_ARRAY));
+    }
+
+    @Test
+    void whenUsingIsArrayNullOrEmpty2_thenCorrect() {
+        assertTrue(isArrayNullOrEmpty2(NULL_ARRAY));
+        assertTrue(isArrayNullOrEmpty2(EMPTY_ARRAY));
+        assertFalse(isArrayNullOrEmpty2(STR_ARRAY));
+
+        //primitive array won't work:
+        //assertFalse(isArrayNullOrEmpty2(INT_ARRAY));
+    }
+
+    @Test
+    void whenUsingArrayUtils_thenCorrect() {
+        assertTrue(ArrayUtils.isEmpty(NULL_ARRAY));
+        assertTrue(ArrayUtils.isEmpty(EMPTY_ARRAY));
+        assertFalse(ArrayUtils.isEmpty(STR_ARRAY));
+        //primitive array
+        assertFalse(ArrayUtils.isEmpty(INT_ARRAY));
+    }
+}