FieldOrderedComparator.java

package io.katharsis.resource.information.field;

import com.fasterxml.jackson.annotation.JsonPropertyOrder;
import io.katharsis.resource.field.ResourceField;

import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;

/**
 * Is used when a resource class is annotated with {@link JsonPropertyOrder}.
 */
public class FieldOrderedComparator implements Comparator<ResourceField> {

    private final Map<String, Integer> fieldNames;
    private final boolean alphabetic;

    public FieldOrderedComparator(String[] orderedValues, boolean alphabetic) {
        this.fieldNames = new HashMap<>();
        this.alphabetic = alphabetic;

        init(orderedValues);
    }

    private void init(String[] orderedValues) {
        for (int i = 0; i < orderedValues.length; i++) {
            this.fieldNames.put(orderedValues[i], i);
        }
    }

    @Override
    public int compare(ResourceField o1, ResourceField o2) {
        if (fieldNames.containsKey(o1.getJsonName())) {
            if (fieldNames.containsKey(o2.getJsonName())) {
                return fieldNames.get(o1.getJsonName()) - fieldNames.get(o2.getJsonName());
            } else {
                return -1;
            }
        } else {
            if (alphabetic) {
                return o1.getJsonName().compareToIgnoreCase(o2.getJsonName());
            } else {
                return 1;
            }
        }
    }
}