arthurshur@gmail.com (#13265)

* Creating a deep vs shallow copy of an object in Java

* Creating a deep vs shallow copy of an object in Java

* Baeldung article converting number bases

* Baeldung article converting number bases

core-java-modules/core-java-lang-5/README.md

@@ -12,3 +12,4 @@ This module contains articles about core features in the Java language
 - [Infinity in Java](https://www.baeldung.com/java-infinity)
 - [Type Parameter vs Wildcard in Java Generics](https://www.baeldung.com/java-generics-type-parameter-vs-wildcard)
 - [Convert Between int and char in Java](https://www.baeldung.com/java-convert-int-char)
+- 

core-java-modules/core-java-lang-5/src/main/java/com/baeldung/convertnumberbases/ConvertNumberBases.java

@@ -0,0 +1,69 @@
+package com.baeldung.convertnumberbases;
+
+public class ConvertNumberBases {
+
+    public static String convertNumberToNewBase(String number, int base, int newBase){
+        return Integer.toString(Integer.parseInt(number, base), newBase);
+    }
+    public static String convertNumberToNewBaseCustom(String num, int base, int newBase) {
+        int decimalNumber = convertFromAnyBaseToDecimal(num, base);
+        return convertFromDecimalToBaseX(decimalNumber, newBase);
+    }
+
+    public static String convertFromDecimalToBaseX(int num, int newBase) {
+
+        String result = "";
+        int remainder;
+        while (num > 0) {
+            remainder = num % newBase;
+            if (newBase == 16) {
+                if (remainder == 10)
+                    result += 'A';
+                else if (remainder == 11)
+                    result += 'B';
+                else if (remainder == 12)
+                    result += 'C';
+                else if (remainder == 13)
+                    result += 'D';
+                else if (remainder == 14)
+                    result += 'E';
+                else if (remainder == 15)
+                    result += 'F';
+                else
+                    result += remainder;
+            } else
+                result += remainder;
+
+            num /= newBase;
+        }
+        return new StringBuffer(result).reverse().toString();
+    }
+
+    public static int convertFromAnyBaseToDecimal(String num, int base) {
+
+        if (base < 2 || (base > 10 && base != 16))
+            return -1;
+
+        int val = 0;
+        int power = 1;
+
+        for (int i = num.length() - 1; i >= 0; i--) {
+            int digit = charToDecimal(num.charAt(i));
+
+            if (digit < 0 || digit >= base)
+                return -1;
+
+            val += digit * power;
+            power = power * base;
+        }
+
+        return val;
+    }
+
+    public static int charToDecimal(char c) {
+        if (c >= '0' && c <= '9')
+            return (int) c - '0';
+        else
+            return (int) c - 'A' + 10;
+    }
+}

core-java-modules/core-java-lang-5/src/main/java/com/baeldung/deepshallowcopy/SchoolDeepCopy.java

@@ -0,0 +1,20 @@
+package com.baeldung.deepshallowcopy;
+
+public class SchoolDeepCopy  implements Cloneable{
+    public String name;
+    public SchoolDeepCopy(String name){
+        this.name = name;
+    }
+
+    protected Object clone() throws  CloneNotSupportedException{
+        return super.clone();
+    }
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+}

core-java-modules/core-java-lang-5/src/main/java/com/baeldung/deepshallowcopy/SchoolShallowCopy.java

@@ -0,0 +1,16 @@
+package com.baeldung.deepshallowcopy;
+
+public class SchoolShallowCopy {
+    public String name;
+    public SchoolShallowCopy(String name){
+        this.name = name;
+    }
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+}

core-java-modules/core-java-lang-5/src/main/java/com/baeldung/deepshallowcopy/StudentDeepCopy.java

@@ -0,0 +1,55 @@
+package com.baeldung.deepshallowcopy;
+
+public class StudentDeepCopy implements Cloneable{
+    public String firstName;
+    public String lastName;
+    public String level;
+    public SchoolDeepCopy school;
+
+
+    public StudentDeepCopy(String firstName, String lastName, String level, SchoolDeepCopy school){
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.level = level;
+        this.school = school;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public String getLevel() {
+        return level;
+    }
+
+    public void setLevel(String level) {
+        this.level = level;
+    }
+
+    public SchoolDeepCopy getSchool() {
+        return school;
+    }
+
+    public void setSchool(SchoolDeepCopy school) {
+        this.school = school;
+    }
+    @Override
+    protected Object clone() throws CloneNotSupportedException {
+        StudentDeepCopy student = (StudentDeepCopy) super.clone();
+        student.school = (SchoolDeepCopy) school.clone();
+        return student;
+    }
+
+}

core-java-modules/core-java-lang-5/src/main/java/com/baeldung/deepshallowcopy/StudentShallowCopy.java

@@ -0,0 +1,53 @@
+package com.baeldung.deepshallowcopy;
+
+public class StudentShallowCopy implements Cloneable{
+    public String firstName;
+    public String lastName;
+    public String level;
+    public SchoolShallowCopy school;
+
+
+    public StudentShallowCopy(String firstName, String lastName, String level, SchoolShallowCopy school){
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.level = level;
+        this.school = school;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public String getLevel() {
+        return level;
+    }
+
+    public void setLevel(String level) {
+        this.level = level;
+    }
+
+    public SchoolShallowCopy getSchool() {
+        return school;
+    }
+
+    public void setSchool(SchoolShallowCopy school) {
+        this.school = school;
+    }
+    @Override
+    protected Object clone() throws CloneNotSupportedException {
+        return super.clone();
+    }
+
+}

core-java-modules/core-java-lang-5/src/test/java/com/baeldung/convertnumberbases/ConvertNumberBasesUnitTest.java

@@ -0,0 +1,20 @@
+package com.baeldung.convertnumberbases;
+
+import static com.baeldung.convertnumberbases.ConvertNumberBases.convertNumberToNewBase;
+import static com.baeldung.convertnumberbases.ConvertNumberBases.convertNumberToNewBaseCustom;
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class ConvertNumberBasesUnitTest {
+
+    @Test
+    void whenConvertingBase10NumberToBase5_ThenResultShouldBeDigitsInBase5() {
+        assertEquals(convertNumberToNewBase("89", 10, 5), "324");
+    }
+    @Test
+    void whenConvertingBase2NumberToBase8_ThenResultShouldBeDigitsInBase8() {
+        assertEquals(convertNumberToNewBaseCustom("11001000", 2, 8), "310");
+    }
+
+}

core-java-modules/core-java-lang-5/src/test/java/com/baeldung/deepshallowcopy/StudentDeepCopyUnitTest.java

@@ -0,0 +1,28 @@
+package com.baeldung.deepshallowcopy;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class StudentDeepCopyUnitTest {
+
+
+    @Test
+    void whenDeepCopying_thenCopyObjectMakesCopyOfReferencedObjectInSourceObject(){
+        SchoolDeepCopy ug = new SchoolDeepCopy("University of Ghana");
+        StudentDeepCopy studentOne = new StudentDeepCopy("Abena", "Kojo","200L", ug );
+        StudentDeepCopy studentTwo = null;
+
+        try{
+            studentTwo = (StudentDeepCopy) studentOne.clone();
+        } catch (CloneNotSupportedException e){
+            e.printStackTrace();
+        }
+
+        assertNotSame(studentOne.getSchool(),studentTwo.getSchool());
+        studentTwo.getSchool().setName("University of Nigeria");
+        assertNotEquals(studentOne.getSchool().getName(), studentTwo.getSchool().getName());
+
+    }
+
+}

core-java-modules/core-java-lang-5/src/test/java/com/baeldung/deepshallowcopy/StudentShallowCopyUnitTest.java

@@ -0,0 +1,26 @@
+package com.baeldung.deepshallowcopy;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class StudentShallowCopyUnitTest {
+
+    @Test
+    void whenShallowCopying_thenCopyObjectAndSourceObjectShareSameReferencedObject(){
+        SchoolShallowCopy ug = new SchoolShallowCopy("University of Ghana");
+        StudentShallowCopy studentOne = new StudentShallowCopy("Abena", "Kojo","200L", ug );
+        StudentShallowCopy studentTwo = null;
+
+        try{
+            studentTwo = (StudentShallowCopy) studentOne.clone();
+        } catch (CloneNotSupportedException e){
+            e.printStackTrace();
+        }
+
+        assertSame(studentOne.getSchool(),studentTwo.getSchool());
+        studentTwo.getSchool().setName("University of Nigeria");
+        assertEquals(studentOne.getSchool().getName(), studentTwo.getSchool().getName());
+    }
+
+}