### Import Statement Ordering Example

Source: https://github.com/fasterxml/jackson/blob/main/contribution/jackson-coding-style-guide.md

Demonstrates the recommended order for import statements: JDK, third-party, Jackson core types, and component-specific types. Static imports follow the same ordering.

```Java
import java.io.*;           // JDK imports
import java.util.*;

import org.junit.*;         // General 3rd party imports

import com.fasterxml.jackson.annotation.*;  // Jackson core types: annotations

import com.fasterxml.jackson.core.*;        // Jackson core types: core
import com.fasterxml.jackson.databind.*;    // Jackson core types: databind

import com.fasterxml.jackson.other.modules.*; // and some Component-specific imports (if any)

// same mechanism for static imports

...static import statements...
```

--------------------------------

### Gradle Dependency Management with Jackson BOM

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Configure your Gradle project to use the Jackson BOM for version management. This example demonstrates how to import the BOM and declare Jackson modules without explicit versions.

```gradle
plugins {
    id 'java'
}
repositories {
    mavenCentral()
}
dependencies {
    implementation platform("tools.jackson:jackson-bom:3.0.0")
    // Now declare Jackson modules WITHOUT versions
    implementation "tools.jackson.core:jackson-databind"
}
```

--------------------------------

### Configure ObjectMapper with Builder and Modules

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Example of constructing a JSON-handling ObjectMapper using the builder pattern, including adding modules and configuring streaming JSON escaping.

```java
final JsonMapper mapper = JsonMapper.builder() // format-specific builders
   .addModule(new JodaModule()) // to use Joda date/time types
   .enable(JsonWriteFeature.ESCAPE_NON_ASCII) // configure streaming JSON-escaping
   .build();
```

--------------------------------

### Maven Dependency Management with Jackson BOM

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Use the Jackson BOM to manage compatible versions of Jackson modules in your Maven project. This example shows how to import the BOM and declare jackson-databind without specifying a version.

```xml
<project>
  <!-- ... -->
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>tools.jackson</groupId>
        <artifactId>jackson-bom</artifactId>
        <version>3.0.0</version>
        <scope>import</scope>
        <type>pom</type>
      </dependency>   
   </dependencies>
  </dependencyManagement>

  <!-- ... -->
  <dependencies>
    <dependency>
      <groupId>tools.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
    </dependency>
    <!-- jackson-core and jackson-annotations transitive dependencies -->
  </dependencies>
<project>
```

--------------------------------

### Configure RecyclerPool for TokenStreamFactory

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Explicitly configure the recycler pool on the factory builder, for example, using JsonRecyclerPools.threadLocalPool(), to align with specific performance characteristics.

```java
JsonFactory f = JsonFactory.builder()
    .recyclerPool(JsonRecyclerPools.threadLocalPool())
    .build();

JsonMapper mapper = JsonMapper.builder(f).build();
```

--------------------------------

### Reconfigure ObjectMapper using Rebuild

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Demonstrates how to create a re-configured instance of an existing ObjectMapper by using its rebuild() method and applying new settings.

```java
JsonMapper mapper2 = mapper.rebuild()
   .enable(SerializationFeature.INDENT_OUTPUT)
   .build();
```

--------------------------------

### Configure Serialization Inclusion with Builder

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Illustrates how to configure serialization inclusion (e.g., NON_NULL) using the builder pattern, specifically for property and content inclusion.

```java
ObjectMapper mapper = JsonMapper.builder()
      .changeDefaultPropertyInclusion(incl -> incl.withValueInclusion(JsonInclude.Include.NON_NULL))
      .changeDefaultPropertyInclusion(incl -> incl.withContentInclusion(JsonInclude.Include.NON_NULL))
      .build();
```

--------------------------------

### Configure Date Format and Time Zone with Builder

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Shows the new builder-based approach for setting the default date format and time zone for an ObjectMapper, replacing older setter methods.

```java
ObjectMapper mapper = JsonMapper.builder()
      .defaultDateFormat(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ"))
      .defaultTimeZone(TimeZone.getDefault())
      .build();
```

--------------------------------

### Instantiate YAMLMapper

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Construct format-specific mappers like YAMLMapper by passing a YAMLFactory instance or using the default constructor.

```java
new YAMLMapper(new YAMLFactory());
```

```java
new YAMLMapper();
```

```java
new YAMLMapper(YAMLFactory().builder()
    // configure
    .build());
```

--------------------------------

### Configure TokenStreamFactory Features

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Use JsonFactory.builder() to configure features like disabling auto-close for the target stream.

```java
JsonFactory f = JsonFactory.builder()
    .disable(StreamWriteFeature.AUTO_CLOSE_TARGET)
    .build();
```

--------------------------------

### Configure Default Serialization/Deserialization Views

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Use MapperBuilder.defaultSerializationView() and defaultDeserializationView() to set default views for serialization and deserialization.

```java
ObjectMapper mapper = JsonMapper.builder()
    .defaultSerializationView(Views.Public.class)
    .defaultDeserializationView(Views.Public.class)
    .build();
```

--------------------------------

### Reconfigure TokenStreamFactory

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Use rebuild() on an existing TokenStreamFactory to create a new builder for further configuration, such as enabling strict duplicate detection.

```java
JsonFactory f2 = f.rebuild()
    .enable(StreamWriteFeature.STRICT_DUPLICATE_DETECTION)
    .build();
```

--------------------------------

### Configure Buffer Recycling Pool in Jackson 3

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

To revert to Jackson 2's thread-local buffer recycling behavior or to use a non-recycling pool, explicitly configure the RecyclerPool when building the JsonFactory. This is useful if profiling indicates overhead from the default deque-based pool.

```java
JsonFactory factory = JsonFactory.builder()
    .recyclerPool(JsonRecyclerPools.threadLocalPool())
    .build();

JsonMapper mapper = JsonMapper.builder(factory)
    .build();
```

```java
JsonFactory factory = JsonFactory.builder()
    .recyclerPool(JsonRecyclerPools.nonRecyclingPool())
    .build();
```

--------------------------------

### Configure ObjectMapper Field Visibility

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Use JsonMapper.builder().changeDefaultVisibility() to configure field visibility, setting it to NONE.

```java
ObjectMapper mapper = JsonMapper.builder()
    .changeDefaultVisibility(vc ->
        vc.withFieldVisibility(JsonAutoDetect.Visibility.NONE))
.build();
```

--------------------------------

### Configure ObjectMapper Default Typing

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Use JsonMapper.builder().activateDefaultTypingAsProperty() to configure default typing. The type validator is built using BasicPolymorphicTypeValidator.builder().

```java
ObjectMapper mapper = JsonMapper.builder()
    .activateDefaultTypingAsProperty(typeValidator, DefaultTyping.NON_CONCRETE_AND_ARRAYS, "@class")
.build();
```

```java
var typeValidator = BasicPolymorphicTypeValidator.builder()
        .allowIfSubType("my.package.base.name.")
        .allowIfSubType("java.util.concurrent.")
        .allowIfSubTypeIsArray()
        // ...
        .build();
```

--------------------------------

### ObjectCodec Removal and Replacement

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

The `com.fasterxml.jackson.core.ObjectCodec` interface has been removed from Jackson 3.0. It is replaced by two new interfaces: `tools.jackson.core.ObjectReadContext` and `tools.jackson.core.ObjectWriteContext`.

```java
// com.fasterxml.jackson.core.ObjectCodec is removed in Jackson 3.0.
// Replaced by tools.jackson.core.ObjectReadContext and tools.jackson.core.ObjectWriteContext.
```

--------------------------------

### Configure Java 8 Date/Time Handling with DateTimeFeature

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Configure Java 8 Date/Time handling in Jackson 3.x using the new DateTimeFeature enumeration. This replaces module-specific JavaTimeFeature or renamed DeserializationFeature/SerializationFeature.

```java
ObjectMapper MAPPER = JsonMapper.builder()
    .enable(DateTimeFeature.WRITE_DATES_WITH_ZONE_ID)
    .build();
```

--------------------------------

### Pass Customized TokenStreamFactory to ObjectMapper

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

Pass a pre-configured TokenStreamFactory instance to the JsonMapper.builder() constructor when creating an ObjectMapper.

```java
JsonFactory f = JsonFactory.builder()
   // configure
   .build();
ObjectMapper mapper = JsonMapper.builder(f)
   // configure
   .build();
```

--------------------------------

### Format Detection Functionality Removal

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

The auto-detection of data format functionality (e.g., `DataFormatDetector` in `jackson-core`) has been dropped in Jackson 3.0 due to complexity and lack of usage. No direct replacement is provided.

```java
// Format detection functionality (e.g., DataFormatDetector) is removed in Jackson 3.0.
```

--------------------------------

### JsonGenerator getCodec() Replacement

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

In Jackson 3.0, `JsonGenerator.getCodec()` is replaced by `objectWriteContext()`. This method provides access to the serialization context.

```java
// In Jackson 3.0, JsonGenerator.getCodec() is replaced with objectWriteContext()
// Example usage would involve obtaining the context from a JsonGenerator instance.
```

--------------------------------

### JsonParser getCodec() Replacement

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

The `JsonParser.getCodec()` method has been replaced with `objectReadContext()` in Jackson 3.0. This provides access to the deserialization context.

```java
// In Jackson 3.0, JsonParser.getCodec() is replaced with objectReadContext()
// Example usage would involve obtaining the context from a JsonParser instance.
```

--------------------------------

### ObjectMapper copy() Removal

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

The `ObjectMapper.copy()` method has been removed in Jackson 3.0. Creating differently configured instances should now be done using the builder pattern.

```java
// In Jackson 3.0, ObjectMapper.copy() is removed.
// Use the builder pattern to create new ObjectMapper instances with specific configurations.
```

--------------------------------

### ObjectMapper canDeserialize/canSerialize Removal

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

The `ObjectMapper.canDeserialize()` and `ObjectMapper.canSerialize()` methods have been removed in Jackson 3.0 as they could not be reliably implemented.

```java
// ObjectMapper.canDeserialize() and ObjectMapper.canSerialize() are removed in Jackson 3.0.
```

--------------------------------

### MappingJsonFactory Removal

Source: https://github.com/fasterxml/jackson/blob/main/jackson3/MIGRATING_TO_JACKSON_3.md

The `com.fasterxml.jackson.databind.MappingJsonFactory` class has been removed in Jackson 3.0. Its functionality is no longer needed or supported in the same way.

```java
// com.fasterxml.jackson.databind.MappingJsonFactory is removed in Jackson 3.0.
```