从 JSONArray java 中删除重复项 [关闭]

Question

我有一个带有 json 对象集合的 JSONArray。我想从列表中删除重复项。问题似乎很简单。但是其他堆栈溢出答案中的代码似乎很大。

有人为我提供任何解决方案来处理这个问题并让代码更精简。

JSONArray jsonElement1 = new JSONArray("[{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-28T18:37:00.000Z\"},\"sort\":[1576653361740],\"_score\":null},{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-29T18:35:00.000Z\"},\"sort\":[1576653361740],\"_score\":null},{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-30T18:41:00.000Z\"},\"sort\":[1576653361739],\"_score\":null},{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-30T18:41:00.000Z\"},\"sort\":[1576653361739],\"_score\":null},{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-28T18:37:00.000Z\"},\"sort\":[1576653361740],\"_score\":null}]");

转换后：

[
{"_index":"sales_csv","_source":{"Order Date":"2016-01-28T18:37:00.000Z"},"sort":[1576653361740],"_score":null},
{"_index":"sales_csv","_source":{"Order Date":"2016-01-29T18:35:00.000Z"},"sort":[1576653361740],"_score":null},
{"_index":"sales_csv","_source":{"Order Date":"2016-01-30T18:41:00.000Z"},"sort":[1576653361739],"_score":null},
{"_index":"sales_csv","_source":{"Order Date":"2016-01-30T18:41:00.000Z"},"sort":[1576653361739],"_score":null},
{"_index":"sales_csv","_source":{"Order Date":"2016-01-28T18:37:00.000Z"},"sort":[1576653361740],"_score":null}
]

我想从 JSONArray 中删除重复项。

需要的输出：

[
{"_index":"sales_csv","_source":{"Order Date":"2016-01-28T18:37:00.000Z"},"sort":[1576653361740],"_score":null},
{"_index":"sales_csv","_source":{"Order Date":"2016-01-29T18:35:00.000Z"},"sort":[1576653361740],"_score":null},
{"_index":"sales_csv","_source":{"Order Date":"2016-01-30T18:41:00.000Z"},"sort":[1576653361739],"_score":null}
]

Answer 1

使用集合框架的Set怎么样？ Set 可以检查重复数据。

对不起，我的代码看起来很糟糕，但我相信你能理解我的代码。

package stackoverflow.test;

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;

import java.util.HashSet;
import java.util.Set;

public class Test1 {

    public static JSONArray sampleJSONArrayData;

    public static void main(String[] args) {
        JSONParser parser = new JSONParser();
        try {
            sampleJSONArrayData = (JSONArray)parser.parse("[\n" +
                    "{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-28T18:37:00.000Z\"}," +
                    "\"sort\":[1576653361740],\"_score\":null},\n" +
                    "{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-29T18:35:00.000Z\"}," +
                    "\"sort\":[1576653361740],\"_score\":null},\n" +
                    "{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-30T18:41:00.000Z\"}," +
                    "\"sort\":[1576653361739],\"_score\":null},\n" +
                    "{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-30T18:41:00.000Z\"}," +
                    "\"sort\":[1576653361739],\"_score\":null},\n" +
                    "{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-28T18:37:00.000Z\"}," +
                    "\"sort\":[1576653361740],\"_score\":null}\n" +
                    "]");
        } catch (Exception e) {
            e.printStackTrace();
        }

        System.out.print("Print original data : ");
        System.out.println(sampleJSONArrayData);

        Set<JSONObject> filterSetData = new HashSet();
        filterSetData.addAll(sampleJSONArrayData);

        System.out.print("Print filtered data : ");
        System.out.println(filteredJSONArray);
    }
}

这是输出

Print original data : [{"_index":"sales_csv","_source":{"Order Date":"2016-01-28T18:37:00.000Z"},"sort":[1576653361740],"_score":null},{"_index":"sales_csv","_source":{"Order Date":"2016-01-29T18:35:00.000Z"},"sort":[1576653361740],"_score":null},{"_index":"sales_csv","_source":{"Order Date":"2016-01-30T18:41:00.000Z"},"sort":[1576653361739],"_score":null},{"_index":"sales_csv","_source":{"Order Date":"2016-01-30T18:41:00.000Z"},"sort":[1576653361739],"_score":null},{"_index":"sales_csv","_source":{"Order Date":"2016-01-28T18:37:00.000Z"},"sort":[1576653361740],"_score":null}]
Print filtered data : [[{"_index":"sales_csv","_source":{"Order Date":"2016-01-28T18:37:00.000Z"},"sort":[1576653361740],"_score":null}, {"_index":"sales_csv","_source":{"Order Date":"2016-01-29T18:35:00.000Z"},"sort":[1576653361740],"_score":null}, {"_index":"sales_csv","_source":{"Order Date":"2016-01-30T18:41:00.000Z"},"sort":[1576653361739],"_score":null}]]

Answer 2

我不确定您正在使用 JSONArray 的 lib，但从中收集唯一值应该相对简单。

此示例显示使用 Jackson 将 JSON 读入 JsonNode，如果您只是想根据每行的 toString 检查是否相等，您可以创建一个值的 HashSet 以过滤掉重复项。

final String json
        = "[{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-28T18:37:00.000Z\"},\"sort\":[1576653361740],\"_score\":null},{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-29T18:35:00.000Z\"},\"sort\":[1576653361740],\"_score\":null},{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-30T18:41:00.000Z\"},\"sort\":[1576653361739],\"_score\":null},{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-30T18:41:00.000Z\"},\"sort\":[1576653361739],\"_score\":null},{\"_index\":\"sales_csv\",\"_source\":{\"Order Date\":\"2016-01-28T18:37:00.000Z\"},\"sort\":[1576653361740],\"_score\":null}]";

final Set<String> result = new HashSet<>();
final com.fasterxml.jackson.databind.JsonNode jsonNode
        = new com.fasterxml.jackson.databind.ObjectMapper()
            .readValue(json, com.fasterxml.jackson.databind.JsonNode.class);
jsonNode.forEach(t -> {
        result.add(t.toString());
    });
result.forEach(System.out::println);

Answer 3

使用Set with String key，把所有东西都放进去，然后get。