Bael 7184 (#15325)

* implementing BAEL-6833

* implementation for BAEL-7115

* feedback fixes

* Moving code folder as per feedback

* renaming logic class folder name

* code implementation

---------

Co-authored-by: technoddy <mail.technoddy@gmail.com>

core-java-modules/core-java-lang-oop-generics/pom.xml

@@ -37,8 +37,8 @@
     </build>
 
     <properties>
-        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.source>17</maven.compiler.source>
-        <maven.compiler.target>1.8</maven.compiler.target>
+        <maven.compiler.target>17</maven.compiler.target>
     </properties>
 
 </project>

core-java-modules/core-java-lang-oop-generics/src/main/java/com/baeldung/generics/classtype/CollectionWithAndWithoutGenerics.java

@@ -0,0 +1,33 @@
+package com.baeldung.generics.classtype;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class CollectionWithAndWithoutGenerics {
+
+    public static void main(String[] args) {
+        withoutGenerics();
+    }
+
+    private static void withoutGenerics() {
+        List container = new ArrayList();
+        container.add(1);
+        container.add("2");
+        container.add("string");
+
+        for (int i = 0; i < container.size(); i++) {
+            int val = (int) container.get(i);
+        }
+    }
+
+    public static void withGenerics() {
+        List<Integer> container = new ArrayList();
+        container.add(1);
+        container.add(2);
+        container.add(3);
+
+        for (int i = 0; i < container.size(); i++) {
+            int val = container.get(i);
+        }
+    }
+}

core-java-modules/core-java-lang-oop-generics/src/main/java/com/baeldung/generics/classtype/ContainerTypeFromReflection.java

@@ -0,0 +1,13 @@
+package com.baeldung.generics.classtype;
+
+public class ContainerTypeFromReflection<T> {
+    private T content;
+
+    public ContainerTypeFromReflection(T content) {
+        this.content = content;
+    }
+
+    public Class<?> getClazz() {
+        return this.content.getClass();
+    }
+}

core-java-modules/core-java-lang-oop-generics/src/main/java/com/baeldung/generics/classtype/ContainerTypeFromTypeParameter.java

@@ -0,0 +1,13 @@
+package com.baeldung.generics.classtype;
+
+public class ContainerTypeFromTypeParameter<T> {
+    private Class<T> clazz;
+
+    public ContainerTypeFromTypeParameter(Class<T> clazz) {
+        this.clazz = clazz;
+    }
+
+    public Class<T> getClazz() {
+        return this.clazz;
+    }
+}

core-java-modules/core-java-lang-oop-generics/src/main/java/com/baeldung/generics/classtype/TypeToken.java

@@ -0,0 +1,17 @@
+package com.baeldung.generics.classtype;
+
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+
+public abstract class TypeToken<T> {
+    private Type type;
+
+    protected TypeToken(){
+        Type superclass = getClass().getGenericSuperclass();
+        this.type = ((ParameterizedType) superclass).getActualTypeArguments()[0];
+    }
+
+    public Type getType() {
+        return type;
+    }
+}

core-java-modules/core-java-lang-oop-generics/src/test/java/com/baeldung/classtype/GenericClassTypeUnitTest.java

@@ -0,0 +1,47 @@
+package com.baeldung.classtype;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.generics.classtype.ContainerTypeFromReflection;
+import com.baeldung.generics.classtype.ContainerTypeFromTypeParameter;
+import com.baeldung.generics.classtype.TypeToken;
+
+public class GenericClassTypeUnitTest {
+
+    @Test
+    public void givenContainerClassWithGenericType_whenTypeParameterUsed_thenReturnsClassType() {
+        var stringContainer = new ContainerTypeFromTypeParameter<>(String.class);
+        Class<String> containerClass = stringContainer.getClazz();
+
+        assertEquals(containerClass, String.class);
+    }
+
+    @Test
+    public void givenContainerClassWithGenericType_whenReflectionUsed_thenReturnsClassType() {
+        var stringContainer = new ContainerTypeFromReflection<>("Hello Java");
+        Class<?> stringClazz = stringContainer.getClazz();
+        assertEquals(stringClazz, String.class);
+
+        var integerContainer = new ContainerTypeFromReflection<>(1);
+        Class<?> integerClazz = integerContainer.getClazz();
+        assertEquals(integerClazz, Integer.class);
+    }
+
+    @Test
+    public void giveContainerClassWithGenericType_whenTypeTokenUsed_thenReturnsClassType() {
+        class ContainerTypeFromTypeToken extends TypeToken<List<String>> {
+        }
+
+        var container = new ContainerTypeFromTypeToken();
+        ParameterizedType type = (ParameterizedType) container.getType();
+        Type actualTypeArgument = type.getActualTypeArguments()[0];
+
+        assertEquals(actualTypeArgument, String.class);
+    }
+}