BAEL-3511 : Default parameters in Java (#8317)

* Added Assertj dependency

* Default parameter example POJO and test class

core-java-modules/core-java-lang-2/src/main/java/com/baeldung/defaultparams/Tea.java

@@ -0,0 +1,61 @@
+package com.baeldung.defaultparams;
+
+public class Tea {
+
+    static final int DEFAULT_TEA_POWDER = 1; // add 1 tbsp tea powder by default
+
+    private String name; // mandatory
+    private int milk; // ml
+    private boolean herbs; // add herbs or don't
+    private int sugar; // tbsp
+    private int teaPowder; // tbsp
+
+    public Tea(String name, int milk, boolean herbs, int sugar, int teaPowder) {
+        this.name = name;
+        this.milk = milk;
+        this.herbs = herbs;
+        this.sugar = sugar;
+        this.teaPowder = teaPowder;
+    }
+
+    // when tea powder is not provided by client, use default value
+    public Tea(String name, int milk, boolean herbs, int sugar) {
+        this(name, milk, herbs, sugar, DEFAULT_TEA_POWDER);
+    }
+
+    // when sugar is not provided by client, don't add it
+    public Tea(String name, int milk, boolean herbs) {
+        this(name, milk, herbs, 0);
+    }
+
+    // when herbs is not provided by client, don't add it
+    public Tea(String name, int milk) {
+        this(name, milk, false);
+    }
+
+    // when milk is not provided by client, don't add it
+    public Tea(String name) {
+        this(name, 0);
+    }   
+
+    public String getName() {
+        return name;
+    }
+
+    public int getMilk() {
+        return milk;
+    }
+
+    public boolean isHerbs() {
+        return herbs;
+    }
+
+    public int getSugar() {
+        return sugar;
+    }
+
+    public int getTeaPowder() {
+        return teaPowder;
+    }
+
+}

core-java-modules/core-java-lang-2/src/test/java/com/baeldung/defaultparams/TeaUnitTest.java

@@ -0,0 +1,20 @@
+package com.baeldung.defaultparams;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+
+public class TeaUnitTest {
+    
+    @Test
+    public void whenTeaWithOnlyName_thenCreateDefaultTea() {
+        Tea blackTea = new Tea("Black Tea");
+
+        assertThat(blackTea.getName()).isEqualTo("Black Tea");
+        assertThat(blackTea.getMilk()).isEqualTo(0);
+        assertThat(blackTea.isHerbs()).isFalse();
+        assertThat(blackTea.getSugar()).isEqualTo(0);
+        assertThat(blackTea.getTeaPowder()).isEqualTo(Tea.DEFAULT_TEA_POWDER);
+    }
+
+}