Merge branch 'master' into master

2023-06-02 16:23:25 +03:00
parent 7bfc898d3e 13f8588022
commit 2c0482c409
136 changed files with 2488 additions and 618 deletions
@@ -7,3 +7,5 @@ This module contains articles about the Java List collection
 - [Finding All Duplicates in a List in Java](https://www.baeldung.com/java-list-find-duplicates)
 - [Moving Items Around in an Arraylist](https://www.baeldung.com/java-arraylist-move-items)
 - [Check if a List Contains an Element From Another List in Java](https://www.baeldung.com/java-check-elements-between-lists)
+- [Array vs. List Performance in Java](https://www.baeldung.com/java-array-vs-list-performance)
+- [Set Default Value for Elements in List](https://www.baeldung.com/java-list-set-default-values)
@@ -1,2 +1,3 @@
 ## Relevant Articles
 - [Copying All Keys and Values From One Hashmap Onto Another Without Replacing Existing Keys and Values](https://www.baeldung.com/java-copy-hashmap-no-changes)
+- [Convert Hashmap to JSON Object in Java](https://www.baeldung.com/java-convert-hashmap-to-json-object)
@@ -0,0 +1,76 @@
+package java.com.baeldung.objecttomap;
+import com.google.gson.Gson;
+import org.junit.Assert;
+import org.junit.Test;
+import wiremock.com.fasterxml.jackson.core.type.TypeReference;
+import wiremock.com.fasterxml.jackson.databind.ObjectMapper;
+import wiremock.com.google.common.reflect.TypeToken;
+import java.lang.reflect.Field;
+import java.util.HashMap;
+import java.util.Map;
+
+public class ObjectToMapUnitTest {
+    Employee employee = new Employee("John", 3000.0);
+
+    @Test
+    public void givenJavaObject_whenUsingReflection_thenConvertToMap() throws IllegalAccessException {
+        Map<String, Object> map = convertUsingReflection(employee);
+        Assert.assertEquals(employee.getName(), map.get("name"));
+        Assert.assertEquals(employee.getSalary(), map.get("salary"));
+    }
+
+    private Map<String, Object> convertUsingReflection(Object object) throws IllegalAccessException {
+        Map<String, Object> map = new HashMap<>();
+        Field[] fields = object.getClass().getDeclaredFields();
+
+        for (Field field : fields) {
+            field.setAccessible(true);
+            map.put(field.getName(), field.get(object));
+        }
+
+        return map;
+    }
+
+    @Test
+    public void givenJavaObject_whenUsingJackson_thenConvertToMap() {
+        ObjectMapper objectMapper = new ObjectMapper();
+        Map<String, Object> map = objectMapper.convertValue(employee, new TypeReference<Map<String, Object>>() {});
+        Assert.assertEquals(employee.getName(), map.get("name"));
+        Assert.assertEquals(employee.getSalary(), map.get("salary"));
+    }
+
+    @Test
+    public void givenJavaObject_whenUsingGson_thenConvertToMap() {
+        Gson gson = new Gson();
+        String json = gson.toJson(employee);
+        Map<String, Object> map = gson.fromJson(json, new TypeToken<Map<String, Object>>() {}.getType());
+        Assert.assertEquals(employee.getName(), map.get("name"));
+        Assert.assertEquals(employee.getSalary(), map.get("salary"));
+    }
+
+    private static class Employee {
+        private String name;
+        private Double salary;
+
+        public Employee(String name, Double salary) {
+            this.name = name;
+            this.salary = salary;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public Double getSalary() {
+            return salary;
+        }
+
+        public void setSalary(Double age) {
+            this.salary = salary;
+        }
+    }
+}
@@ -12,3 +12,5 @@ This module contains articles about core Java input/output(IO) APIs.
 - [Storing Java Scanner Input in an Array](https://www.baeldung.com/java-store-scanner-input-in-array)
 - [How to Take Input as String With Spaces in Java Using Scanner?](https://www.baeldung.com/java-scanner-input-with-spaces)
 - [Write Console Output to Text File in Java](https://www.baeldung.com/java-write-console-output-file)
+- [What’s the difference between Scanner next() and nextLine() methods?](https://www.baeldung.com/java-scanner-next-vs-nextline)
+- [Handle NoSuchElementException When Reading a File Through Scanner](https://www.baeldung.com/java-scanner-nosuchelementexception-reading-file)
@@ -3,33 +3,81 @@ package com.baeldung.regex.z_regexp;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;

+import java.util.regex.Pattern;
 public class ZRegularExpressionUnitTest {
    @Test
    public void givenCreditCardNumber_thenReturnIfMatched() {
        String creditCardNumber = "1234567890123456";
+        String creditCardNumber2 = "1234567890123456\n";
        String pattern = "\\d{16}\\z";
-        Assertions.assertTrue(creditCardNumber.matches(pattern));
+        Assertions.assertTrue(Pattern.compile(pattern).matcher(creditCardNumber).find());
+        Assertions.assertFalse(Pattern.compile(pattern).matcher(creditCardNumber2).find());
+    }
+
+    @Test
+    public void givenCreditCardNumber_thenReturnIfNotMatched() {
+        String creditCardNumber = "1234567890123456\n";
+        String pattern = "\\d{16}\\z";
+        Assertions.assertFalse(Pattern.compile(pattern).matcher(creditCardNumber).find());
    }

    @Test
    public void givenLogOutput_thenReturnIfMatched() {
        String logLine = "2022-05-01 14:30:00,123 INFO Some log message";
        String pattern = ".*message\\z";
-        Assertions.assertTrue(logLine.matches(pattern));
+        Assertions.assertTrue(Pattern.compile(pattern).matcher(logLine).find());
    }

+    @Test
+    public void givenLogOutput_thenReturnIfNotMatched() {
+        String logLine = "2022-05-01 14:30:00,123 INFO Some log message\n";
+        String pattern = ".*message\\z";
+        Assertions.assertFalse(Pattern.compile(pattern).matcher(logLine).find());
+    }
    @Test
    public void givenEmailMessage_thenReturnIfMatched() {
        String myMessage = "Hello HR, I hope i can write to Baeldung\n";
-        String pattern = ".*Baeldung\\s*\\Z";
-        Assertions.assertTrue(myMessage.matches(pattern));
+        String myMessage2 = "Hello HR, I hope\n i can write to Baeldung";
+        String pattern = ".*Baeldung\\Z";
+        String pattern2 = ".*hope\\Z";
+        Assertions.assertTrue(Pattern.compile(pattern).matcher(myMessage).find());
+        Assertions.assertFalse(Pattern.compile(pattern2).matcher(myMessage2).find());
+    }
+
+    @Test
+    public void givenEmailMessage_thenReturnIfNotMatched() {
+        String myMessage = "Hello HR, I hope\n i can write to Baeldung";
+        String pattern = ".*hope\\Z";
+        Assertions.assertFalse(Pattern.compile(pattern).matcher(myMessage).find());
    }

    @Test
    public void givenFileExtension_thenReturnIfMatched() {
-        String fileName = "image.jpeg";
+        String fileName = "image.jpeg\n";
+        String fileName2 = "image2.jpeg\n.png";
        String pattern = ".*\\.jpeg\\Z";
-        Assertions.assertTrue(fileName.matches(pattern));
+        Assertions.assertTrue(Pattern.compile(pattern).matcher(fileName).find());
+        Assertions.assertFalse(Pattern.compile(pattern).matcher(fileName2).find());
    }

-}
+    @Test
+    public void givenFileExtension_thenReturnIfNotMatched() {
+        String fileName = "image2.jpeg\n.png";
+        String pattern = ".*\\.jpeg\\Z";
+        Assertions.assertFalse(Pattern.compile(pattern).matcher(fileName).find());
+    }
+    @Test
+    public void givenURL_thenReturnIfMatched() {
+        String url = "https://www.example.com/api/endpoint\n";
+        String pattern = ".*/endpoint$";
+        Assertions.assertTrue(Pattern.compile(pattern).matcher(url).find());
+    }
+
+    @Test
+    public void givenSentence_thenReturnIfMatched() {
+        String sentence = "Hello, how are you?";
+        String pattern = ".*[.?!]$";
+        Assertions.assertTrue(Pattern.compile(pattern).matcher(sentence).find());
+    }
+
+}
@@ -7,3 +7,4 @@
 - [Deserialization Vulnerabilities in Java](https://www.baeldung.com/java-deserialization-vulnerabilities)
 - [Serialization Validation in Java](https://www.baeldung.com/java-validate-serializable)
 - [What Is the serialVersionUID?](https://www.baeldung.com/java-serial-version-uid)
+- [Java Serialization: readObject() vs. readResolve()](https://www.baeldung.com/java-serialization-readobject-vs-readresolve)
@@ -0,0 +1,21 @@
+package com.baeldung.readresolvevsreadobject;
+
+import java.io.ObjectStreamException;
+import java.io.Serializable;
+
+public class Singleton implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+    private static Singleton INSTANCE = new Singleton();
+
+    private Singleton() {
+    }
+
+    public static Singleton getInstance() {
+        return INSTANCE;
+    }
+
+    private Object readResolve() throws ObjectStreamException {
+        return INSTANCE;
+    }
+}
@@ -0,0 +1,59 @@
+package com.baeldung.readresolvevsreadobject;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+
+public class User implements Serializable {
+
+    private static final long serialVersionUID = 3659932210257138726L;
+    private String userName;
+    private String password;
+
+    public String getUserName() {
+        return userName;
+    }
+
+    public void setUserName(String userName) {
+        this.userName = userName;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    @Override
+    public String toString() {
+        return "User [userName=" + userName + ", password=" + password + "]";
+    }
+
+    public User() {
+    }
+
+    public User(String userName, String password) {
+        super();
+        this.userName = userName;
+        this.password = password;
+    }
+
+    private void writeObject(ObjectOutputStream oos) throws IOException {
+        this.password = "xyz" + password;
+        oos.defaultWriteObject();
+    }
+
+    private void readObject(ObjectInputStream aInputStream)
+            throws ClassNotFoundException, IOException {
+        aInputStream.defaultReadObject();
+        this.password = password.substring(3);
+    }
+
+    private Object readResolve() {
+        return this;
+    }
+
+}
@@ -0,0 +1,47 @@
+package com.baeldung.readresolvevsreadobject;
+
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+public class SingletonUnitTest {
+
+    @Test
+    public void testSingletonObj_withNoReadResolve() throws ClassNotFoundException, IOException {
+        // Serialization
+        FileOutputStream fos = new FileOutputStream("singleton.ser");
+        ObjectOutputStream oos = new ObjectOutputStream(fos);
+        Singleton actualSingletonObject = Singleton.getInstance();
+        oos.writeObject(actualSingletonObject);
+
+        // Deserialization
+        Singleton deserializedSingletonObject = null;
+        FileInputStream fis = new FileInputStream("singleton.ser");
+        ObjectInputStream ois = new ObjectInputStream(fis);
+        deserializedSingletonObject = (Singleton) ois.readObject();
+        // remove readResolve() from Singleton class and uncomment this to test.
+        //assertNotEquals(actualSingletonObject.hashCode(), deserializedSingletonObject.hashCode());
+    }
+
+    @Test
+    public void testSingletonObj_withCustomReadResolve()
+            throws ClassNotFoundException, IOException {
+        // Serialization
+        FileOutputStream fos = new FileOutputStream("singleton.ser");
+        ObjectOutputStream oos = new ObjectOutputStream(fos);
+        Singleton actualSingletonObject = Singleton.getInstance();
+        oos.writeObject(actualSingletonObject);
+
+        // Deserialization
+        Singleton deserializedSingletonObject = null;
+        FileInputStream fis = new FileInputStream("singleton.ser");
+        ObjectInputStream ois = new ObjectInputStream(fis);
+        deserializedSingletonObject = (Singleton) ois.readObject();
+        assertEquals(actualSingletonObject.hashCode(), deserializedSingletonObject.hashCode());
+    }
+}
@@ -0,0 +1,52 @@
+package com.baeldung.readresolvevsreadobject;
+
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+public class UserUnitTest {
+
+    @Test
+    public void testDeserializeObj_withOverriddenReadObject()
+            throws ClassNotFoundException, IOException {
+        // Serialization
+        FileOutputStream fos = new FileOutputStream("user.ser");
+        ObjectOutputStream oos = new ObjectOutputStream(fos);
+        User acutalObject = new User("Sachin", "Kumar");
+        oos.writeObject(acutalObject);
+
+        // Deserialization
+        User deserializedUser = null;
+        FileInputStream fis = new FileInputStream("user.ser");
+        ObjectInputStream ois = new ObjectInputStream(fis);
+        deserializedUser = (User) ois.readObject();
+        assertNotEquals(deserializedUser.hashCode(), acutalObject.hashCode());
+        assertEquals(deserializedUser.getUserName(), "Sachin");
+        assertEquals(deserializedUser.getPassword(), "Kumar");
+    }
+
+    @Test
+    public void testDeserializeObj_withDefaultReadObject()
+            throws ClassNotFoundException, IOException {
+        // Serialization
+        FileOutputStream fos = new FileOutputStream("user.ser");
+        ObjectOutputStream oos = new ObjectOutputStream(fos);
+        User acutalObject = new User("Sachin", "Kumar");
+        oos.writeObject(acutalObject);
+
+        // Deserialization
+        User deserializedUser = null;
+        FileInputStream fis = new FileInputStream("user.ser");
+        ObjectInputStream ois = new ObjectInputStream(fis);
+        deserializedUser = (User) ois.readObject();
+        assertNotEquals(deserializedUser.hashCode(), acutalObject.hashCode());
+        assertEquals(deserializedUser.getUserName(), "Sachin");
+        // remove readObject() from User class and uncomment this to test.
+        //assertEquals(deserializedUser.getPassword(), "xyzKumar");
+    }
+}