org.apache.arrow.vector.util.JsonStringHashMap.java Source code

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Here is the source code for org.apache.arrow.vector.util.JsonStringHashMap.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.arrow.vector.util;

import java.util.LinkedHashMap;
import java.util.Map;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

/*
 * Simple class that extends the regular java.util.HashMap but overrides the
 * toString() method of the HashMap class to produce a JSON string instead
 */
public class JsonStringHashMap<K, V> extends LinkedHashMap<K, V> {

    private static ObjectMapper mapper;

    static {
        mapper = new ObjectMapper();
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (!(obj instanceof Map)) {
            return false;
        }
        Map other = (Map) obj;
        if (this.size() != other.size()) {
            return false;
        }
        for (K key : this.keySet()) {
            if (this.get(key) == null) {
                if (other.get(key) == null) {
                    continue;
                } else {
                    return false;
                }
            }
            if (!this.get(key).equals(other.get(key))) {
                return false;
            }
        }
        return true;
    }

    @Override
    public final String toString() {
        try {
            return mapper.writeValueAsString(this);
        } catch (JsonProcessingException e) {
            throw new IllegalStateException("Cannot serialize hash map to JSON string", e);
        }
    }
}