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Merge pull request #7489 from M-Abdelbaset/public-access-modifier 

BAEL-3148
This commit is contained in:
Erik Pragt 2019-09-01 21:44:58 +10:00 committed by GitHub
parent 5563175efa 4dd44a29d8
commit 5473d1c8d4
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5 changed files with 211 additions and 0 deletions
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13
core-java-modules/core-java-lang-oop-2/pom.xml
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@ -14,6 +14,19 @@
<relativePath>../../parent-java</relativePath>
</parent>
<dependencies>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>${h2.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<properties>
<h2.version>1.4.199</h2.version>
</properties>
<build>
<finalName>core-java-lang-oop-2</finalName>
<resources>

31
core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/ListOfThree.java Normal file
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@ -0,0 +1,31 @@
package com.baeldung.accessmodifiers.publicmodifier;
import java.util.AbstractList;
import java.util.Arrays;
public class ListOfThree<E> extends AbstractList<E> {
private static final int LENGTH = 3;
private Object[] elements;
public ListOfThree(E[] data) {
if(data == null
|| data.length != LENGTH)
throw new IllegalArgumentException();
this.elements = Arrays.copyOf(data, data.length); //shallow copy
}
@Override
@SuppressWarnings("unchecked")
public E get(int index) {
return (E)elements[index];
}
@Override
public int size() {
return LENGTH;
}
}

7
core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/SpecialCharacters.java Normal file
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@ -0,0 +1,7 @@
package com.baeldung.accessmodifiers.publicmodifier;
public class SpecialCharacters {
public static final String SLASH = "/";
}

67
core-java-modules/core-java-lang-oop-2/src/main/java/com/baeldung/accessmodifiers/publicmodifier/Student.java Normal file
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package com.baeldung.accessmodifiers.publicmodifier;
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Date;
public class Student {
private StudentGrade grade; //new data representation
// private int grade; //old data representation
private String name;
private int age;
public void setGrade(int grade) {
this.grade = new StudentGrade(grade);
}
public int getGrade() {
return this.grade.getGrade().intValue(); //int is returned for backward compatibility
}
public Connection getConnection() throws SQLException {
final String URL = "jdbc:h2:~/test";
return DriverManager.getConnection(URL, "sa", "");
}
public void setAge(int age) {
if (age < 0 || age > 150) {
throw new IllegalArgumentException();
}
this.age = age;
}
public int getAge() {
return age;
}
@Override
public String toString() {
return this.name;
}
private class StudentGrade {
private BigDecimal grade = BigDecimal.ZERO;
private Date updatedAt;
public StudentGrade(int grade) {
this.grade = new BigDecimal(grade);
this.updatedAt = new Date();
}
public BigDecimal getGrade() {
return grade;
}
public Date getDate() {
return updatedAt;
}
}
}

93
core-java-modules/core-java-lang-oop-2/src/test/java/com/baeldung/accessmodifiers/PublicAccessModifierUnitTest.java Normal file
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@ -0,0 +1,93 @@
package com.baeldung.accessmodifiers;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestInstance;
import org.junit.jupiter.api.TestInstance.Lifecycle;
import com.baeldung.accessmodifiers.publicmodifier.ListOfThree;
import com.baeldung.accessmodifiers.publicmodifier.Student;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@TestInstance(Lifecycle.PER_CLASS)
public class PublicAccessModifierUnitTest {
@Test
public void whenUsingBigDecimalIntValueMethod_correspondingIntIsReturned() {
assertEquals(0, new BigDecimal(0).intValue()); //instance member
}
@Test
public void whenUsingIntegerMaxValueField_maxPossibleIntValueIsReturned() {
assertEquals(2147483647, Integer.MAX_VALUE); //static field
}
@Test
public void whenChangingStudentInternalRepresentation_clientCodeWillNotBreak() {
Student student = new Student();
student.setGrade(100);
assertEquals(100, student.getGrade());
}
@Test
public void whenUsingEntrySet_keyValuePairsAreReturned() {
Map<String, String> mapObject = new HashMap<String, String>();
mapObject.put("name", "Alex");
for(Map.Entry<String, String> entry : mapObject.entrySet()) {
assertEquals("name", entry.getKey());
assertEquals("Alex", entry.getValue());
}
}
@Test
public void whenUsingStringToLowerCase_stringTurnsToLowerCase() {
assertEquals("alex", "ALEX".toLowerCase());
}
@Test
public void whenParsingStringOne_parseIntReturns1() {
assertEquals(1, Integer.parseInt("1"));
}
@Test
public void whenConnectingToH2_connectionInstanceIsReturned() throws SQLException {
final String url = "jdbc:h2:~/test";
Connection conn = DriverManager.getConnection(url, "sa", "");
assertNotNull(conn);
}
@Test
public void whenCreatingCustomList_concreteAndInheritedMethodsWork() {
String[] dataSet1 = new String[] {"zero", "one", "two"};
List<String> list1 = new ListOfThree<String>(dataSet1);
//our implemented methods
assertEquals("one", list1.get(1));
assertEquals(3, list1.size());
//inherited implementations
assertEquals(1, list1.indexOf("one"));
String[] dataSet2 = new String[] {"two", "zero", "one"};
List<String> list2 = new ListOfThree<String>(dataSet2);
assertTrue(list1.containsAll(list2));
}
}