.

ch01/src/main/AbstractPerson.java

@@ -0,0 +1,29 @@
+package main;
+
+public abstract class AbstractPerson {
+    protected String name;
+    protected String phoneNumber;
+
+    protected AbstractPerson() {};
+
+    protected AbstractPerson(String name, String phoneNumber) {
+        this.name = name;
+        this.phoneNumber = phoneNumber;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getPhoneNumber() {
+        return phoneNumber;
+    }
+
+    public void setPhoneNumber(String phoneNumber) {
+        this.phoneNumber = phoneNumber;
+    }
+}

ch01/src/main/ArrayFlattening.java

@@ -0,0 +1,32 @@
+package main;
+
+import java.util.*;
+import java.lang.reflect.*;
+
+public class ArrayFlattening {
+
+    public <T> T concat(Class<?> type, Object... arguments) {
+
+        if (arguments.length == 0) {
+            return null;
+        }
+
+        List<Object> list = new ArrayList<>();
+        for (int i = 0; i < arguments.length; i++) {
+            if (arguments[i].getClass().isArray()) {
+                int len = Array.getLength(arguments[i]);
+                for (int j = 0; j < len; j++) {
+                    list.add(Array.get(arguments[i], j));
+                }
+            } else {
+                list.add(arguments[i]);
+            }
+        }
+
+        Object flattenedArray = Array.newInstance(type, list.size());
+        for (int i = 0; i < list.size(); i++) {
+            Array.set(flattenedArray, i, list.get(i));
+        }
+        return (T)flattenedArray;
+    }
+}

ch01/src/main/ArrayReflection.java

@@ -0,0 +1,24 @@
+package main;
+
+import java.lang.reflect.Array;
+
+public class ArrayReflection {
+    public static void main(String[] args) {
+        int[] arr = {1, 2, 3, 4, 5};
+        if (arr.getClass().isArray()) {
+            System.out.println("===== is Array =====");
+            Class<?> clazz = arr.getClass().getComponentType();
+            int len = Array.getLength(arr);
+
+            for (int i = 0; i < len; i++) {
+                System.out.println(Array.get(arr, i));
+            }
+        }
+    }
+
+    public Object getArrayEliment(Object array, int index) {
+        int len = Array.getLength(array);
+        index = (index < 0) ? len + index : index;
+        return Array.get(array, index);
+    }
+}

ch01/src/main/FieldPrint.java

@@ -0,0 +1,29 @@
+package main;
+
+import java.lang.reflect.Field;
+
+public class FieldPrint {
+    public static void main(String[] args) {
+        Student std = new Student("John", "010-6483-7446", "A");
+
+        Class<?> clazz = std.getClass();
+        Field[] fields = clazz.getDeclaredFields();
+        for (var field : fields) {
+            System.out.println("Field Name : " + field.getName() + ", Field Type : " + field.getType().getName());
+        }
+
+        System.out.println("==============");
+
+        fields = clazz.getFields();
+        for (var field : fields) {
+            System.out.println("Field Name : " + field.getName() + ", Field Type : " + field.getType().getName());
+        } 
+
+        fields = clazz.getSuperclass().getFields();
+        System.out.println("==============");
+
+        for (var field: fields) {
+            System.out.println("Field Name : " + field.getName() + ", Field Type : " + field.getType().getName());
+        }
+    }
+}

ch01/src/main/IllegalAccessExceptione.java

@@ -0,0 +1,5 @@
+package main;
+
+public class IllegalAccessExceptione {
+
+}

ch01/src/main/ObjectSizeCalculator.java

@@ -0,0 +1,57 @@
+package main;
+
+import java.lang.reflect.*;
+
+public class ObjectSizeCalculator {
+    private static final long HEADER_SIZE = 12;
+    private static final long REFERENCE_SIZE = 4;
+
+    public static void main(String[] args) {
+        sizeOfObject(new Student("John", "010-6483-7446", "A"));
+    }
+
+    public static long sizeOfObject(Object input) {
+        long size = 0;
+        Field[] fields = input.getClass().getDeclaredFields();
+        for (var field : fields) {
+            field.setAccessible(true);
+            if (!field.isSynthetic()) {
+                if (field.getType().isPrimitive()) {
+                    size += sizeOfPrimitiveType(field.getType());
+                } else {
+                    try {
+                        String value = (String)field.get(input);
+                        size += sizeOfString(value);
+                    } catch (IllegalArgumentException | IllegalAccessException e) {
+                        size += 0;
+                    } 
+                }
+            }
+        }
+        return size + HEADER_SIZE + REFERENCE_SIZE;
+    }
+
+
+/*************** Helper methods ********************************/    
+    private static long sizeOfPrimitiveType(Class<?> primitiveType) {
+        if (primitiveType.equals(int.class)) {
+            return 4;
+        } else if (primitiveType.equals(long.class)) {
+            return 8;
+        } else if (primitiveType.equals(float.class)) {
+            return 4;
+        } else if (primitiveType.equals(double.class)) {
+            return 8;
+        } else if (primitiveType.equals(byte.class)) {
+            return 1;
+        } else if (primitiveType.equals(short.class)) {
+            return 2;
+        }
+        throw new IllegalArgumentException(String.format("Type: %s is not supported", primitiveType));
+    }
+
+    private static long sizeOfString(String inputString) {
+        int stringBytesSize = inputString.getBytes().length;
+        return HEADER_SIZE + REFERENCE_SIZE + stringBytesSize;
+    }
+}

ch01/src/main/Student.java

@@ -0,0 +1,19 @@
+package main;
+
+public class Student extends AbstractPerson {
+    private String classCode;
+
+    public Student(String name, String phoneNumber, String classCode) {
+        super(name, phoneNumber);
+        this.classCode = classCode;
+    }
+
+    public String getClassCode() {
+        return classCode;
+    }
+
+    public void setClassCode(String classCode) {
+        this.classCode = classCode;
+    }
+
+}