只需执行以下操作即可：
import java.io.File;import java.io.FileWriter;import java.io.IOException;import org.json.JSONException;import org.json.JSONObject;import com.fasterxml.jackson.databind.ObjectMapper;public class Test { public static void main(String[] args) throws JSONException, IOException { ObjectMapper mapper = new ObjectMapper(); String key = "key1"; //whatever JSonObject jo = new JSonObject("{key1:"val1", key2:"val2"}"); //Read from file JSonObject root = mapper.readValue(new File("json_file"), JSONObject.class); String val_newer = jo.getString(key); String val_older = root.getString(key); //Compare values if(!val_newer.equals(val_older)) { //Update value in objectroot.put(key,val_newer);//Write into the file try (FileWriter file = new FileWriter("json_file")) { file.write(root.toString()); System.out.println("Successfully updated json object to file...!!"); } } }}
