how do I append value to an existing json array ?
I have existing json array with below values
{
"test": [
1,
2,
3,
4
]
}
I wanted to add "0" in to the json array so that the new json array would look like
{
"test": [
0,
1,
2,
3,
4
]
}
Using Java and the Jackson library, you can deserialize the (json) String to a Java object, add the entry, and then serialize the modified object (print it to Json format).
In example, with this code
package json;
import java.util.Collections;
import java.util.List;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
public class UseJson {
public static void main(String[] args) throws Exception {
ObjectMapper om = new ObjectMapper();
String json = "{\r\n" +
" \"test\": [\r\n" +
" 1,\r\n" +
" 2,\r\n" +
" 3,\r\n" +
" 4\r\n" +
" ]\r\n" +
"} ";
System.out.println("json="+json);
Wrap val = om.readValue( json, Wrap.class);
System.out.println("read val="+val);
val.test.add(0);
Collections.sort(val.test);
System.out.println("val="+val);
om.enable(SerializationFeature.INDENT_OUTPUT);
String json2 = om.writeValueAsString(val);
System.out.println("json2="+json2);
}
}
class Wrap {
public List<Integer> test;
@Override
public String toString() {
return "Wrap[test=" + test + "]";
}
}
you get..
json={
"test": [
1,
2,
3,
4
]
}
read val=Wrap[test=[1, 2, 3, 4]]
val=Wrap[test=[0, 1, 2, 3, 4]]
json2={
"test" : [ 0, 1, 2, 3, 4 ]
}
(to be compiled in a Maven project including jackson-core and jackson-databind)
