Java Quiz 1

reference

Operation‐centered User‐defined Accessed through reference variables

primitive

Value‐centered Predefined Accessed through variables

how do you change a variable from primitive to references with a wrapper class?

"new" Integer rf1 = new Integer("1");

What are the two ways of commenting while coding?

// short comments /* long comment */

= vs ==; How they differ

== is a realtional operator, means equal to = is an assignment compound ?

Objects vs classes

Objects are everything around us, physical or abstract, each characterized by attributes and behaviors/operations; Objects sharing common characteristics are organized and "classified" into a class. While an object is an individual design, a class is an abstraction /model/ blueprint which captures the common behaviors of a set of objects and define a new abstract data type.

what's wrong with this code: two things System.println("Hello world!")

System.out.println("Hello world!") ; out and semi colon

What is a specification in writing a Java code?

a problem / task, should be clear and feasible with no doubt/ ambiguity

integral 5 types

char, byte, short, int, long

Compiler vs assembler

compiler: translates an entire program before executing it

What is an operator in Java?

does the operation, does something to the variable

floating point 2 types

float and double

High-level language vs machine language

high level langauage = what we write in to programs like java machine langauage = binary

What language does a computer understand?

high-level (compiler) assembly (assembler) machine (machine interpreatation) hardware architecture (architecture implementation) logic circuit

Naming rule for identifiers and variables in Java

identifiers: case-senstitve, self-explanatory, letters, digits, _ $, can't start with digit, can't be reserved word

What is a pseudocode?

mixture of english and programming language

What is String in terms of its data type? Is it a primitive data type or not?

predefined (like primitive), but not a primitive data type

Wrapper classes transform _____ into objects

primitive data type

What is the escape character for?

punctuation, new line, tab, quotation

how to get things to go to the command prompt

reference data! public class NameOfFile { public static void main(String[] args) { ...

What is an algorithm?

set of programmable instructions to solve a problem

Attributes

store data that characterizes an object, and they are represented by variables associated with the state of the object.

Boolean

true/false

What is the keyword to create an object by calling a class through a reference variable?

wrapper class???

What are wrapper classes in Java?

wrapper classes transform primitive data types into objects

Advantages of Java over other programming languages

‐ simple and easy to learn(?) ‐ platform portability; write once, run everywhere with JVM ‐ code reusability; once write, use everywhere ‐ extreme security; no viruses attack the host system ‐ extreme reliability, making it possible to develop Web applications ‐ supports multi‐threading, making software development easy ‐ supports Unicode, making people work with non‐English languages ‐ extreme versatility; Java is everywhere! ‐ supports object‐oriented programming (OOP)