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This project aims to provide an easy tool to visualize data flow and objects within the JVM. It is intended for students that are starting to learn programming with Java.
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package me.ruebner.jvisualizer.backend.vm.values;

import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.sun.jdi.ArrayReference;
import com.sun.jdi.ClassNotLoadedException;
import me.ruebner.jvisualizer.backend.vm.json.ArrayElementSerializer;
import me.ruebner.jvisualizer.backend.vm.types.ArrayType;
import me.ruebner.jvisualizer.backend.vm.types.Type;

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

/**
 * Represents an array value on the heap.
 */
public class ArrayReferenceValue extends ReferenceValue {

    /**
     * the list of element values of the array
     */
    @JsonProperty
    @JsonSerialize(using = ArrayElementSerializer.class)
    private final List elements = new ArrayList<>();

    /**
     * the type of the array elements
     */
    @JsonProperty
    private final Type elementType;

    /**
     * Creates a new array value object. To create a new array value object based on an
     * {@link ArrayReference} object, use {@link #fromJdi(ArrayReference)}.
     *
     * @param type the type of the array
     * @param uniqueId the unique id of this value
     * @param elements a list of elements of this array (the elements will be copied to a
     *         new internal list)
     * @param elementType the type of the array elements
     */
    private ArrayReferenceValue(ArrayType type, long uniqueId, List elements, Type elementType) {
        super(type, uniqueId);
        this.elements.addAll(elements);
        this.elementType = elementType;
    }

    /**
     * Creates a new array value object based on a {@link ArrayReference} object.
     *
     * @param jdiArrayReference the JDI array reference object
     * @return the new array value object based on {@code jdiArrayReference}
     */
    public static ArrayReferenceValue fromJdi(ArrayReference jdiArrayReference) {
        ArrayReferenceValue newValue;
        try {
            newValue = new ArrayReferenceValue(
                    (ArrayType) Type.fromJdi(jdiArrayReference.type()),
                    jdiArrayReference.uniqueID(),
                    new ArrayList<>(),
                    Type.fromJdi(((com.sun.jdi.ArrayType) jdiArrayReference.type()).componentType())
            );
        } catch (ClassNotLoadedException ex) {
            newValue = new ArrayReferenceValue(
                    (ArrayType) Type.fromJdi(jdiArrayReference.type()),
                    jdiArrayReference.uniqueID(),
                    new ArrayList<>(),
                    new Type(((com.sun.jdi.ArrayType) jdiArrayReference.type()).componentTypeName()) {
                    }
            );
        }
        newValue.cache();

        for (var value : jdiArrayReference.getValues()) {
            newValue.elements.add(Value.fromJdi(value));
        }

        return newValue;
    }

    /**
     * Retrieves an unmodifiable list of the elements of the array.
     *
     * @return the list of elements of the array
     */
    public List getElements() {
        return Collections.unmodifiableList(elements);
    }

    /**
     * Retrieves the size of the array.
     *
     * @return the size of the array
     */
    @JsonProperty
    public int getLength() {
        return elements.size();
    }

    /**
     * Retrieves the type of the array's elements.
     *
     * @return the type of the array's elements.
     */
    public Type getElementType() {
        return elementType;
    }

    @Override
    public String toString() {
        return "{"
                + elements.stream()
                .limit(7)
                .map(Value::toString)
                .collect(Collectors.joining(", "))
                + (elements.size() > 7 ? ", ..." : "")
                + "}";
    }
}