Chapter 1: Building blocks Flashcards
The java command launches the Java Virtual Machine (JVM) before running bytecode. If false, why?
True
The javac command converts .java source files into .class bytecode. If false, why?
True
The jar command is used to package multiple files together in Java. If false, why?
True
The javadoc command generates documentation for Java source code. If false, why?
True
A Java class can have both methods and fields. If false, why?
True
The void keyword in Java means a method does not return any value. If false, why?
True
Parameters in a method provide values from the calling method. If false, why?
True
The javac command is used to execute Java programs. If false, why?
False – The javac command compiles source code into bytecode, but does not execute it.
An object and a class in Java are the same thing. If false, why?
False – A class is a blueprint, while an object is an instance of that class.
A reference variable in Java holds the actual object. If false, why?
False – A reference variable holds the memory address of an object, not the object itself.
A Java class must always contain at least one method. If false, why?
False – A class can be empty, such as public class Animal {}.
The simplest Java class must include a main method. If false, why?
False – A Java class only needs to be defined; a main method is required only for execution.
The String class in Java is a primitive data type. If false, why?
False – String is a class, not a primitive type; it is an object in Java.
The public keyword restricts a method’s access to only within the same class. If false, why?
False – public allows the method to be accessed from other classes.
A single-line comment in Java starts with // and extends to the end of the line.
True
A multiline comment in Java starts with /** and ends with **/.
(Correct: It starts with /* and ends with */.)
Javadoc comments can only be used inside methods.
(Correct: Javadoc comments can be used for classes, methods, and fields.)
Java ignores all comments, including Javadoc comments, at runtime and compile time.
(Correct: Javadoc comments can be processed by the Javadoc tool.)
A Java source file can contain multiple public classes.
(Correct: Only one top-level class can be public.)
If a class is not declared public, it must be declared private.
(Correct: A top-level class can be package-private if no access modifier is specified.)
A Java file with a public class does not have to match the filename.
(Correct: The filename must match the public class name exactly.)
The Javadoc @author tag is required for all classes.
(Correct: It is optional and used for documentation purposes.)
Comments can slow down Java code execution.
(Correct: Comments are ignored by the compiler and do not affect execution speed.
A Javadoc comment must include an @param tag.
(Correct: The @param tag is only needed if documenting method parameters.)
