For example my JSON file look like this;
{
"Test1": {
"A": {},
"B": "1",
"C": "2",
"D": "3"
},
"Test2": {
"A": {},
"B": "4",
"C": "5",
"D": "6"
},
"Test3": {
"A": {},
"B": "7",
"C": "8",
"D": "9"
},
"Test4": {
"A": {},
"B": "10",
"C": "11",
"D": "12"
}
...
...
}
This would have been simple if the file only contained a few records, but in my case I'm dealing with thousands of records. For simpler version I've used gson library but not sure how I could load this JSON file which has unique name for each record into Java.
***************UPDATE*******************************
I now managed to read it raw and Map the data. However, still have a minor issue.
This is the code I used to Map
ObjectMapper mapper = new ObjectMapper();
File jsonFile = new File(jsonFilePath);
Map<String, Object> mapObject = mapper.readValue(jsonFile,
new TypeReference<Map<String, Object>>() {
});
System.out.println(mapObject.get("Test1"));
I'm getting below results, which is fine. However, not sure how I could obtain the data within "values" of the map.
{A={}, B=1, C=2, D=3}
I tried below to re-map but it's failing as expected, because the keys no longer are surrounded by double quotes (see above)!
Map<String, Object> nestedObject = mapper.readValue(
mapObject.get("Test1").toString(),
new TypeReference<Map<String, Object>>() {
});
If you know your objects all contain the same keys A, B, C and D then you could create a class that maps a single object
class MyEntry {
/**
* You've tagged the question "gson" but your example code uses Jackson so I've
* written this class with Jackson annotations rather than Gson ones.
*/
@JsonProperty("A")
public Object a; // or a more specific type if you know one
@JsonProperty("B")
public String b;
@JsonProperty("C")
public String c;
@JsonProperty("D")
public String d;
}
and then unmarshal the JSON as a Map<String, MyEntry>
Map<String, MyEntry> mapObject = mapper.readValue(jsonFile,
new TypeReference<Map<String, MyEntry>>() {
});
System.out.println(mapObject.get("Test1").b); // prints 1
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