add some gson deserialization examples

gson/src/test/java/org/baeldung/gson/deserialization/Foo.java

@@ -9,6 +9,10 @@ public class Foo {
         this.stringValue = stringValue;
     }
 
+    public Foo(final String stringValue) {
+        this.stringValue = stringValue;
+    }
+
     public Foo() {
         super();
     }
@@ -19,27 +23,33 @@ public class Foo {
     public int hashCode() {
         final int prime = 31;
         int result = 1;
-        result = prime * result + intValue;
+        result = (prime * result) + intValue;
-        result = prime * result + ((stringValue == null) ? 0 : stringValue.hashCode());
+        result = (prime * result) + ((stringValue == null) ? 0 : stringValue.hashCode());
         return result;
     }
 
     @Override
     public boolean equals(final Object obj) {
-        if (this == obj)
+        if (this == obj) {
             return true;
-        if (obj == null)
+        }
+        if (obj == null) {
             return false;
-        if (getClass() != obj.getClass())
+        }
+        if (getClass() != obj.getClass()) {
             return false;
+        }
         final Foo other = (Foo) obj;
-        if (intValue != other.intValue)
+        if (intValue != other.intValue) {
             return false;
+        }
         if (stringValue == null) {
-            if (other.stringValue != null)
+            if (other.stringValue != null) {
                 return false;
-        } else if (!stringValue.equals(other.stringValue))
+            }
+        } else if (!stringValue.equals(other.stringValue)) {
             return false;
+        }
         return true;
     }
 

gson/src/test/java/org/baeldung/gson/deserialization/FooInstanceCreator.java

@@ -0,0 +1,14 @@
+package org.baeldung.gson.deserialization;
+
+import java.lang.reflect.Type;
+
+import com.google.gson.InstanceCreator;
+
+public class FooInstanceCreator implements InstanceCreator<Foo> {
+
+    @Override
+    public Foo createInstance(Type type) {
+        return new Foo("sample");
+    }
+
+}

gson/src/test/java/org/baeldung/gson/deserialization/FooWithInner.java

@@ -0,0 +1,24 @@
+package org.baeldung.gson.deserialization;
+
+public class FooWithInner {
+    public int intValue;
+    public String stringValue;
+    public InnerFoo innerFoo;
+
+    public FooWithInner(int intValue, String stringValue, String name) {
+        super();
+        this.intValue = intValue;
+        this.stringValue = stringValue;
+        this.innerFoo = new InnerFoo(name);
+    }
+
+    public class InnerFoo {
+        public String name;
+
+        public InnerFoo(String name) {
+            super();
+            this.name = name;
+        }
+
+    }
+}

gson/src/test/java/org/baeldung/gson/deserialization/test/GsonDeserializationTest.java

@@ -12,6 +12,8 @@ import java.util.Collection;
 
 import org.baeldung.gson.deserialization.Foo;
 import org.baeldung.gson.deserialization.FooDeserializerFromJsonWithDifferentFields;
+import org.baeldung.gson.deserialization.FooInstanceCreator;
+import org.baeldung.gson.deserialization.FooWithInner;
 import org.baeldung.gson.deserialization.GenericFoo;
 import org.junit.Test;
 
@@ -108,4 +110,29 @@ public class GsonDeserializationTest {
         assertEquals(targetObject.stringValue, "seven");
     }
 
+    // new examples
+
+    @Test
+    public void whenDeserializingToNestedObjects_thenCorrect() {
+        final String json = "{\"intValue\":1,\"stringValue\":\"one\",\"innerFoo\":{\"name\":\"inner\"}}";
+
+        final FooWithInner targetObject = new Gson().fromJson(json, FooWithInner.class);
+
+        assertEquals(targetObject.intValue, 1);
+        assertEquals(targetObject.stringValue, "one");
+        assertEquals(targetObject.innerFoo.name, "inner");
+    }
+
+    @Test
+    public void whenDeserializingUsingInstanceCreator_thenCorrect() {
+        final String json = "{\"intValue\":1}";
+
+        final GsonBuilder gsonBldr = new GsonBuilder();
+        gsonBldr.registerTypeAdapter(Foo.class, new FooInstanceCreator());
+        final Foo targetObject = gsonBldr.create().fromJson(json, Foo.class);
+
+        assertEquals(targetObject.intValue, 1);
+        assertEquals(targetObject.stringValue, "sample");
+    }
+
 }