android里面的toJSON方法怎么用？

举个例子：

public class Account {

    private double balance;
    private long accountId;

    public Account(double amout, long id) {
        balance = amout;
        accountId = id;
    }

    public JSONObject toJson() {
        JSONObject object = new JSONObject();
        object.put("balance", balance);
        object.put("id", accountId);
        return object;
    }
}