convert java object to json string online code example

Example 1: convert json string to json object in java

try {
     JSONObject jsonObject = new JSONObject("{\"phonetype\":\"N95\",\"cat\":\"WP\"}");
}catch (JSONException err){
     Log.d("Error", err.toString());
}

Example 2: convert java object to json

Jackson Data-bind depdendency that take care of 
Converting between 
JSON to Java Object 
and 
Java Object to JSON

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.12.0</version>
</dependency>