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Revised: Sat Jun 04 12:48:39 CDT 2016
This page is included in the following Books:
This is a page from the book titled The json-simple Java Library . The book explains how to use the json-simple Java library to generate, transform, and query JSON text. This page provides review questionsand answers for the page titled Json0215: Encoding JSON Strings . Once you study that page, you should be able to answer the review questions in this page.
The questions and the answers in this page are connected by hyperlinks to make it easy for you to navigate from the question to the answer and back again.
The figures and listings (if any) are grouped together. It is recommend that when a question or an answer refers to a figure or a listing, that you open it in a new window tomake it easy to view it while reading the question or the answer.
True or False? Once you have an object of the class named JSONObject , you can call any of the methods defined in the HashMap class on that object.
True or False? The code shown in Listing 1 produced the screen output shown in Figure 1 .
True or False? The code shown in Listing 3 produced the screen output shown in Figure 3 .
What is the meaning of the following two images?
These images were inserted here simply to insert some space between the questions and the answers to keep them from being visible on the screen at thesame time.
This image was also inserted for the purpose of inserting space between the questions and the answers.
True. The code in Listing 3 uses the get method inherited from the HashMap class to get and display the values associated with the keys "name", "age", and "student".
False. The code in Listing 1 produced the output with the compiler error message shown in Figure 2 . The output shown in in Figure 1 was produced by the code shown in Listing 2 . Note the call to the toJSONString method of the JSONObject class to extract the information from the JSONObject object and encode it into a JSON string.
True. The class named JSONObject extends the standard Java class named HashMap . Therefore, the JSONObject class inherits all of the methods defined in the HashMap class.
This section contains Figures that may be referred to by one or more questions or answers.
Figure 1
{"student":true,"name":"Joe","age":21} Figure 2
Code01.java:20: error: no suitable method found for get(no arguments)
String jsonString = jsonObject.get(); Figure 3
Joe
21true This section contains Listings that may be referred to by one or more questions or answers.
Listing 1
import org.json.simple.JSONObject;
class Code01 {public static void main(String[] args){JSONObject jsonObject= new JSONObject();
jsonObject.put("name","Joe");jsonObject.put("age",21);
jsonObject.put("student",true);String jsonString = jsonObject.get();
System.out.println(jsonString);}//end main
}//end class Code01 Listing 2
import org.json.simple.JSONObject;
class Code02 {public static void main(String[] args){JSONObject jsonObject= new JSONObject();
jsonObject.put("name","Joe");jsonObject.put("age",21);
jsonObject.put("student",true);String jsonString = jsonObject.toJSONString();
System.out.println(jsonString);}//end main
}//end class Code02 Listing 3
import org.json.simple.JSONObject;
class Code03 {public static void main(String[] args){JSONObject jsonObject= new JSONObject();
jsonObject.put("name","Joe");jsonObject.put("age",21);
jsonObject.put("student",true);System.out.println(jsonObject.get("name"));
System.out.println(jsonObject.get("age"));System.out.println(jsonObject.get("student"));
}//end main}//end class Code03 This section contains a variety of miscellaneous information.
Financial : Although the Connexions site makes it possible for you to download aPDF file for this module at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, youshould be aware that some of the HTML elements in this module may not translate well into PDF.
I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version ofthe module.
In the past, unknown individuals have copied my modules fromcnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. I neither receive compensationfor those sales nor do I know who does receive compensation. If you purchase such a book, please be aware that it is a copy of a modulethat is freely available on cnx.org and that it was made and published without my prior knowledge.
Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.
-end-
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