regex Java splitting a comma-separated String but ignoring commas within quotes+braces+recursive brackets

Question

I have a string line like this:

valueA,{"property1":"value1","property2":"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]","property3":"value3",.....,"propertyn":"valueN"},valueB,{"property1":"value1","property2":"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]","property3":"value3",.....,"propertyn":"valueN"},valueC,{"property1":"value1","property2":"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]","property3":"value3",.....,"propertyn":"valueN"}

That I want to split by commas

the above string should split into:

valueA
{"property1":"value1","property2":"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]","property3":"value3",.....,"propertyn":"valueN"}
valueB
{"property1":"value1","property2":"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]","property3":"value3",.....,"propertyn":"valueN"}
valueC
{"property1":"value1","property2":"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]","property3":"value3",.....,"propertyn":"valueN"}

Try it but It doesn't split well.

String[] tokens = line.split(",(?=(?:[^\"]*\"[^\"]*\")*[^\"]*$)", -1);

How can I do this?

Answer 1

You could use a simpler approach to use split with ",{" as the separator.

String[] tokens = line.split(",{");

The result would be as follows:

tokens[0] = "valueA"
tokens[1] = "property1":"value1","property2":"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]","property3":"value3",.....,"propertyn":"valueN"}

So the only work left would be to add the starting bracket {

Answer 2

Instead of splitting try to extract the data with a pattern matcher.

String line = "valueA,{\"property1\":\"value1\",\"property2\":\"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]\",\"property3\":\"value3\"},valueB,{\"property1\":\"value1\",\"property2\":\"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]\",\"property3\":\"value3\"},valueC,{\"property1\":\"value1\",\"property2\":\"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]\",\"property3\":\"value3\"}";
Pattern pattern = Pattern.compile("([,]*(value[A-Z])),(\\{\"[\\w\":,\\[\\].]+\"\\})");
Matcher matcher = pattern.matcher(line);
List<String> data = new ArrayList<>();

while (matcher.find()) {
    String key = matcher.group(2);
    String value = matcher.group(3);

    data.add(key);
    data.add(value);

    System.out.println(key);
    System.out.println(value);
}
String[] array = data.toArray(new String[0]);

Resulting output:

valueA
{"property1":"value1","property2":"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]","property3":"value3"}
valueB
{"property1":"value1","property2":"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]","property3":"value3"}
valueC
{"property1":"value1","property2":"[[[1.5,1.7],[1.9,0.7],.....,[0.5,0.9]]]","property3":"value3"}