Deserialization

The deserializer will deserialize every field found in the YAPIONObject and set it back into an instance of an object. This examples will use some code of the Serializer. We will start with our class:

public class Example {
    
    // This will not be saved or loaded as it is 'static'
    private static int i = 0;
    
    // This will not be saved or loaded as it is 'transient'
    private transient long l = 0;
    
    private int integer = 0;

    private String string = "Hello World";

}

Now we add our basic save annotations:

import yapion.annotations.serialize.YAPIONSave;

@YAPIONSave
public class Example {
    
    // This will not be saved or loaded as it is 'static'
    private static int i = 0;
    
    // This will not be saved or loaded as it is 'transient'
    private transient long l = 0;
    
    @YAPIONSave
    private int integer = 0;

    @YAPIONSave
    private String string = "Hello World";

}

Now we need to hint the deserializer what to load:

import yapion.annotations.serialize.YAPIONSave;
import yapion.annotations.deserialize.YAPIONLoad;

@YAPIONSave
@YAPIONLoad
public class Example {
    
    // This will not be saved or loaded as it is 'static'
    private static int i = 0;
    
    // This will not be saved or loaded as it is 'transient'
    private transient long l = 0;
    
    @YAPIONSave
    @YAPIONLoad
    private int integer = 0;

    @YAPIONSave
    @YAPIONLoad
    private String string = "Hello World";

}

The save and load annotations can be combined to the data annotation. This has some limiations. If you use the load and save annotations you need a no args constructor for the object. This is because YAPION needs a way to create an instance of such objects. The result of the constructor call is that each field has the value with which the field is initialized, or the value set in the constructor. Afterwards YAPION can set every value defined in the YAPIONObject. When you use the YAPIONData annotation you do not need to create a no args constructor for the object but if some values are not loaded because they are declared transient or static they will have the java type default value. So numbers are 0, booleans are false and every object is null. For this example we will use the YAPIONData annotation as follows:

import yapion.annotations.object.YAPIONData;

@YAPIONData
public class Example {
    
    // This will not be saved as it is 'static'
    private static int i = 0;
    
    // This will not be saved as it is 'transient'
    private transient long l = 0;
    
    private int integer = 0;

    private String string = "Hello World";

}

Now we will use the same Serialization code from the Serialization example and expand it to handle deserialization as well.

import yapion.hierarchy.types.YAPIONObject;
import yapion.serializing.YAPIONSerializer;
import yapion.serializing.YAPIONDeserializer;

public class ExampleDeserialization {

    public static void main(String[] args) {
        YAPIONObject yapionObject = YAPIONSerializer.serialize(new Example());

        // Now we need to deserialize back to an Example instance
        // The deserializer will return an generic Object and you need to cast it to the type you expect
        Oject object = YAPIONDeserializer.deserialize(yapionObject);

        // Cast the Object:
        Example example = (Example) object;
    }

}

This also works when you ‘extend’ one object from another.

import yapion.annotations.object.YAPIONData;

@YAPIONData
public class ExampleTwo extends Example {

    private String text = "ExampleTwo";

}

Deserializing will look something like this:

import yapion.hierarchy.types.YAPIONObject;
import yapion.serializing.YAPIONSerializer;

public class ExampleSerializationTwo {

    public static void main(String[] args) {
        YAPIONObject yapionObject = YAPIONSerializer.serialize(new ExampleTwo());
    
        // Now we need to deserialize back to an ExampleTwo instance
        // The deserializer will return an generic Object and you need to cast it to the type you expect
        Oject object = YAPIONDeserializer.deserialize(yapionObject);
      
        // Cast the Object:
        ExampleTwo exampleTwo = (ExampleTwo) object;
    }

}