Merge branch 'master' of https://github.com/eugenp/tutorials

2020-04-09 10:09:45 +02:00
parent af0fc5f058 88cc732dc7
commit f630aeed0b
171 changed files with 2295 additions and 225 deletions
@@ -0,0 +1,56 @@
+package com.baeldung.java14.helpfulnullpointerexceptions;
+
+public class HelpfulNullPointerException {
+
+    public static void main(String[] args) {
+        Employee employee = null;
+        employee.getName();
+    }
+
+    public String getEmployeeEmailAddress(Employee employee) {
+        String emailAddress = employee.getPersonalDetails().getEmailAddress().toLowerCase();
+        return emailAddress;
+    }
+
+    static class Employee {
+        String name;
+        PersonalDetails personalDetails;
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public PersonalDetails getPersonalDetails() {
+            return personalDetails;
+        }
+
+        public void setPersonalDetails(PersonalDetails personalDetails) {
+            this.personalDetails = personalDetails;
+        }
+    }
+
+    static class PersonalDetails {
+        String emailAddress;
+        String phone;
+
+        public String getEmailAddress() {
+            return emailAddress;
+        }
+
+        public void setEmailAddress(String emailAddress) {
+            this.emailAddress = emailAddress;
+        }
+
+        public String getPhone() {
+            return phone;
+        }
+
+        public void setPhone(String phone) {
+            this.phone = phone;
+        }
+    }
+}
@@ -0,0 +1,37 @@
+package com.baeldung.java14.helpfulnullpointerexceptions;
+
+import org.junit.Test;
+
+import static com.baeldung.java14.helpfulnullpointerexceptions.HelpfulNullPointerException.Employee;
+import static com.baeldung.java14.helpfulnullpointerexceptions.HelpfulNullPointerException.PersonalDetails;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class HelpfulNullPointerExceptionUnitTest {
+
+    @Test (expected = NullPointerException.class)
+    public void givenAnEmptyPersonalDetails_whenEmailAddressIsAccessed_thenThrowNPE() {
+        var helpfulNPE = new HelpfulNullPointerException();
+
+        var employee = new Employee();
+        employee.setName("Eduard");
+        employee.setPersonalDetails(new PersonalDetails());
+        helpfulNPE.getEmployeeEmailAddress(employee);
+    }
+
+    @Test
+    public void givenCompletePersonalDetails_whenEmailAddressIsAccessed_thenSuccess() {
+        var helpfulNPE = new HelpfulNullPointerException();
+        var emailAddress = "[email protected]";
+
+        var employee = new Employee();
+        employee.setName("Eduard");
+
+        var personalDetails = new PersonalDetails();
+        personalDetails.setEmailAddress(emailAddress.toUpperCase());
+        personalDetails.setPhone("1234");
+        employee.setPersonalDetails(personalDetails);
+
+        assertThat(helpfulNPE.getEmployeeEmailAddress(employee)).isEqualTo(emailAddress);
+    }
+
+}
@@ -0,0 +1,25 @@
+package com.baeldung.concurrent.volatilekeyword;
+
+public class TaskRunner {
+
+    private static int number;
+    private volatile static boolean ready;
+
+    private static class Reader extends Thread {
+
+        @Override
+        public void run() {
+            while (!ready) {
+                Thread.yield();
+            }
+
+            System.out.println(number);
+        }
+    }
+
+    public static void main(String[] args) {
+        new Reader().start();
+        number = 42;
+        ready = true;
+    }
+}
@@ -1,18 +1,17 @@
 package com.baeldung.java8;

-import static org.hamcrest.Matchers.equalTo;
+import com.baeldung.java8.entity.Human;
+import com.google.common.collect.Lists;
+import com.google.common.primitives.Ints;
+import org.junit.Assert;
+import org.junit.Test;

 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.stream.Collectors;

-import org.junit.Assert;
-import org.junit.Test;
-
-import com.baeldung.java8.entity.Human;
-import com.google.common.collect.Lists;
-import com.google.common.primitives.Ints;
+import static org.hamcrest.Matchers.equalTo;

 public class Java8SortUnitTest {

@@ -113,11 +112,11 @@ public class Java8SortUnitTest {
        humans.sort(Comparator.comparing(Human::getName));
        Assert.assertThat(humans.get(0), equalTo(new Human("Jack", 12)));
    }
-    
+
    @Test
    public final void givenStreamNaturalOrdering_whenSortingEntitiesByName_thenCorrectlySorted() {
        final List<String> letters = Lists.newArrayList("B", "A", "C");
-        
+
        final List<String> sortedLetters = letters.stream().sorted().collect(Collectors.toList());
        Assert.assertThat(sortedLetters.get(0), equalTo("A"));
    }
@@ -126,7 +125,7 @@ public class Java8SortUnitTest {
    public final void givenStreamCustomOrdering_whenSortingEntitiesByName_thenCorrectlySorted() {
        final List<Human> humans = Lists.newArrayList(new Human("Sarah", 10), new Human("Jack", 12));
        final Comparator<Human> nameComparator = (h1, h2) -> h1.getName().compareTo(h2.getName());
-        
+
        final List<Human> sortedHumans = humans.stream().sorted(nameComparator).collect(Collectors.toList());
        Assert.assertThat(sortedHumans.get(0), equalTo(new Human("Jack", 12)));
    }
@@ -164,4 +163,48 @@ public class Java8SortUnitTest {
        Assert.assertThat(reverseSortedHumans.get(0), equalTo(new Human("Sarah", 10)));
    }

+    @Test(expected = NullPointerException.class)
+    public final void givenANullElement_whenSortingEntitiesByName_thenThrowsNPE() {
+        final List<Human> humans = Lists.newArrayList(null, new Human("Jack", 12));
+
+        humans.sort((h1, h2) -> h1.getName().compareTo(h2.getName()));
+    }
+
+    @Test
+    public final void givenANullElement_whenSortingEntitiesByNameManually_thenMovesTheNullToLast() {
+        final List<Human> humans = Lists.newArrayList(null, new Human("Jack", 12), null);
+
+        humans.sort((h1, h2) -> {
+            if (h1 == null) return h2 == null ? 0 : 1;
+            else if (h2 == null) return -1;
+
+            return h1.getName().compareTo(h2.getName());
+        });
+
+        Assert.assertNotNull(humans.get(0));
+        Assert.assertNull(humans.get(1));
+        Assert.assertNull(humans.get(2));
+    }
+
+    @Test
+    public final void givenANullElement_whenSortingEntitiesByName_thenMovesTheNullToLast() {
+        final List<Human> humans = Lists.newArrayList(null, new Human("Jack", 12), null);
+
+        humans.sort(Comparator.nullsLast(Comparator.comparing(Human::getName)));
+
+        Assert.assertNotNull(humans.get(0));
+        Assert.assertNull(humans.get(1));
+        Assert.assertNull(humans.get(2));
+    }
+
+    @Test
+    public final void givenANullElement_whenSortingEntitiesByName_thenMovesTheNullToStart() {
+        final List<Human> humans = Lists.newArrayList(null, new Human("Jack", 12), null);
+
+        humans.sort(Comparator.nullsFirst(Comparator.comparing(Human::getName)));
+
+        Assert.assertNull(humans.get(0));
+        Assert.assertNull(humans.get(1));
+        Assert.assertNotNull(humans.get(2));
+    }
 }
@@ -1,8 +1,12 @@
 package com.baeldung.comparelong;

 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
+
 import org.junit.Test;

+import java.util.Objects;
+
 public class CompareLongUnitTest {

    @Test
@@ -32,6 +36,33 @@ public class CompareLongUnitTest {
        assertThat(l1.equals(l2)).isTrue();
    }

+    @Test
+    public void givenLongValuesLessThan128_whenUsingObjectsEquals_thenSuccess() {
+
+        Long l1 = 127L;
+        Long l2 = 127L;
+
+        assertThat(Objects.equals(l1, l2)).isTrue();
+    }
+
+    @Test
+    public void givenLongValuesGreaterOrEqualsThan128_whenUsingObjectsEquals_thenSuccess() {
+
+        Long l1 = 128L;
+        Long l2 = 128L;
+
+        assertThat(Objects.equals(l1, l2)).isTrue();
+    }
+
+    @Test
+    public void givenNullReference_whenUsingObjectsEquals_thenNoException() {
+
+        Long l1 = null;
+        Long l2 = 128L;
+
+        assertThatCode(() -> Objects.equals(l1, l2)).doesNotThrowAnyException();
+    }
+
    @Test
    public void givenLongValuesGreaterOrEqualsThan128_whenUsingComparisonOperator_andLongValue_thenSuccess() {

@@ -1,3 +1,11 @@
+## Core Java Security 
+
+This module contains articles about core Java Security
+
 ### Relevant Articles:

 - [Guide To The Java Authentication And Authorization Service (JAAS)](https://www.baeldung.com/java-authentication-authorization-service)
+- [MD5 Hashing in Java](http://www.baeldung.com/java-md5)
+- [Hashing a Password in Java](https://www.baeldung.com/java-password-hashing)
+- [SHA-256 and SHA3-256 Hashing in Java](https://www.baeldung.com/sha-256-hashing-java)
+- More articles: [[<-- prev]](/core-java-modules/core-java-security)
@@ -16,4 +16,45 @@
        <relativePath>../../parent-java</relativePath>
    </parent>

+    <dependencies>
+
+        <dependency>
+            <groupId>commons-codec</groupId>
+            <artifactId>commons-codec</artifactId>
+            <version>${commons-codec.version}</version>
+        </dependency>
+        
+        <dependency>
+            <groupId>org.bouncycastle</groupId>
+            <artifactId>bcprov-jdk15on</artifactId>
+            <version>${bouncycastle.version}</version>
+        </dependency>
+        
+         <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj-core.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <!-- https://mvnrepository.com/artifact/javax.xml.bind/jaxb-api -->
+        <dependency>
+            <groupId>javax.xml.bind</groupId>
+            <artifactId>jaxb-api</artifactId>
+            <version>2.3.1</version>
+        </dependency>
+
+
+    </dependencies>
+    
+    <properties>
+        <!-- util -->
+        <bouncycastle.version>1.60</bouncycastle.version>
+        <commons-codec.version>1.11</commons-codec.version>
+
+        <!-- testing -->
+        <assertj-core.version>3.10.0</assertj-core.version>
+    </properties>
+
 </project>
@@ -0,0 +1,23 @@
+package com.baeldung.checksums;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.zip.CRC32;
+import java.util.zip.CheckedInputStream;
+import java.util.zip.Checksum;
+
+public class ChecksumUtils {
+
+    public static long getChecksumCRC32(byte[] bytes) {
+        Checksum crc32 = new CRC32();
+        crc32.update(bytes, 0, bytes.length);
+        return crc32.getValue();
+    }
+
+    public static long getChecksumCRC32(InputStream stream, int bufferSize) throws IOException {
+        CheckedInputStream checkedInputStream = new CheckedInputStream(stream, new CRC32());
+        byte[] buffer = new byte[bufferSize];
+        while (checkedInputStream.read(buffer, 0, buffer.length) >= 0) {}
+        return checkedInputStream.getChecksum().getValue();
+    }
+}
@@ -0,0 +1,51 @@
+package com.baeldung.checksums;
+
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ChecksumUtilsUnitTest {
+
+    byte[] arr;
+
+    @Before
+    void setUp() {
+        arr =  new byte[]{0,10,21,20,35,40,120,56,72,22};
+    }
+
+    @Test
+    void givenByteArray_whenChecksumCreated_checkCorrect() {
+
+        long checksum = ChecksumUtils.getChecksumCRC32(arr);
+
+        assertEquals(3915397664L, checksum);
+    }
+
+    @Test
+    void givenTwoDifferentStrings_whenChecksumCreated_checkCollision() {
+
+        String plumless = "plumless";
+        String buckeroo = "buckeroo";
+
+        long plumlessChecksum = ChecksumUtils.getChecksumCRC32(plumless.getBytes());
+        long buckerooChecksum = ChecksumUtils.getChecksumCRC32(buckeroo.getBytes());
+
+        assertEquals(plumlessChecksum, buckerooChecksum);
+    }
+
+    @Test
+    void givenInputString_whenChecksumCreated_checkCorrect() throws IOException {
+
+        InputStream inputStream = new ByteArrayInputStream(arr);
+        long checksum = ChecksumUtils.getChecksumCRC32(inputStream, 10);
+
+        assertEquals(3915397664L, checksum);
+
+    }
+}
@@ -3,17 +3,16 @@
 This module contains articles about core Java Security

 ### Relevant Articles: 
- [MD5 Hashing in Java](http://www.baeldung.com/java-md5)
+
 - [Guide to the Cipher Class](http://www.baeldung.com/java-cipher-class)
 - [Introduction to SSL in Java](http://www.baeldung.com/java-ssl)
 - [Java KeyStore API](http://www.baeldung.com/java-keystore)
 - [Encrypting and Decrypting Files in Java](http://www.baeldung.com/java-cipher-input-output-stream)
- [Hashing a Password in Java](https://www.baeldung.com/java-password-hashing)
 - [SSL Handshake Failures](https://www.baeldung.com/java-ssl-handshake-failures)
- [SHA-256 and SHA3-256 Hashing in Java](https://www.baeldung.com/sha-256-hashing-java)
 - [Enabling TLS v1.2 in Java 7](https://www.baeldung.com/java-7-tls-v12)
 - [The Java SecureRandom Class](https://www.baeldung.com/java-secure-random)
 - [An Introduction to Java SASL](https://www.baeldung.com/java-sasl)
 - [A Guide to Java GSS API](https://www.baeldung.com/java-gss)
 - [Intro to the Java SecurityManager](https://www.baeldung.com/java-security-manager)
+- More articles: [[next -->]](/core-java-modules/core-java-security-2)

@@ -24,24 +24,9 @@
            <version>${assertj-core.version}</version>
            <scope>test</scope>
        </dependency>
-
-        <dependency>
-            <groupId>commons-codec</groupId>
-            <artifactId>commons-codec</artifactId>
-            <version>${commons-codec.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.bouncycastle</groupId>
-            <artifactId>bcprov-jdk15on</artifactId>
-            <version>${bouncycastle.version}</version>
-        </dependency>
    </dependencies>

    <properties>
-        <!-- util -->
-        <bouncycastle.version>1.60</bouncycastle.version>
-        <commons-codec.version>1.11</commons-codec.version>
-
        <!-- testing -->
        <assertj-core.version>3.10.0</assertj-core.version>
    </properties>
@@ -0,0 +1,42 @@
+package com.baeldung.streams.bigdecimals;
+
+import static org.junit.Assert.assertEquals;
+
+import java.math.BigDecimal;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+import org.junit.Test;
+
+public class AddNumbersUnitTest {
+
+    @Test
+    public void givenIntStream_whenSum_thenResultIsCorrect() {
+        IntStream intNumbers = IntStream.range(0, 3);
+        assertEquals(3, intNumbers.sum());
+    }
+
+    @Test
+    public void givenCollectionOfDouble_whenUsingMapToDoubleToSum_thenResultIsCorrect() {
+        List<Double> doubleNumbers = Arrays.asList(23.48, 52.26, 13.5);
+        double result = doubleNumbers.stream()
+            .mapToDouble(Double::doubleValue)
+            .sum();
+        assertEquals(89.24, result, .1);
+    }
+
+    public void givenStreamOfIntegers_whenUsingReduceToSum_thenResultIsCorrect() {
+        Stream<Integer> intNumbers = Stream.of(0, 1, 2);
+        int result = intNumbers.reduce(0, Integer::sum);
+        assertEquals(106, result);
+    }
+
+    public void givenStreamOfBigDecimals_whenUsingReduceToSum_thenResultIsCorrect() {
+        Stream<BigDecimal> bigDecimalNumber = Stream.of(BigDecimal.ZERO, BigDecimal.ONE, BigDecimal.TEN);
+        BigDecimal result = bigDecimalNumber.reduce(BigDecimal.ZERO, BigDecimal::add);
+        assertEquals(11, result);
+    }
+
+}
@@ -0,0 +1,20 @@
+package com.baeldung.guava.mapmaker;
+
+public class Profile {
+    private long id;
+    private String type;
+
+    public Profile(long id, String type) {
+        this.id = id;
+        this.type = type;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public String getName() {
+        return type;
+    }
+
+}
@@ -0,0 +1,13 @@
+package com.baeldung.guava.mapmaker;
+
+public class Session {
+    private long id;
+
+    public Session(long id) {
+        this.id = id;
+    }
+
+    public long getId() {
+        return id;
+    }
+}
@@ -0,0 +1,20 @@
+package com.baeldung.guava.mapmaker;
+
+public class User {
+    private long id;
+    private String name;
+
+    public User(long id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+}
--- a/Show More
+++ b/Show More