Ch1 Welcome to Java

Question 1

What package do the Files and Paths class belong to?

Answer 1

java.nio.file

Question 2

Compile and run the following two classes using the java terminal commands:

• packagea/ClassA
• packageb/ClassB (contains the main method)

Answer 2

• javac packagea/ClassA.java packageb/ClassB.java
• java packageb.ClassB

Question 3

Where does the javac command place the compiled classes by default?

Answer 3

In the same directory as the source code.

Question 4

How can we use the javac command to compile ‘packagea/ClassA’ in the directory ‘classes’

Answer 4

javac -d classes packagea/ClassA.java

Question 5

Compile and run the two classes below using the java terminal commands. Compile them into a directory called ‘classes’.

• packagea/ClassA
• packageb/ClassB (contains the main method)

Answer 5

1. javac -d classes packagea/ClassA.java packageb/ClassB.java
2. java -cp classes packageb.ClassB

Question 6

What options are there to specify the classpath to the java or javac command?

Answer 6

• ‘-cp’
• ‘-classpath’
• ’–class-path’

Question 7

Create a JAR file: ‘myNewFile.jar’ based on the current directory.

Answer 7

jar -cvf myNewFile.jar .
– or –
jar –create –verbose –file myNewFile.jar .

Question 8

Create a JAR file: ‘myNewFile.jar’ based on the directory ‘dir’

Answer 8

jar -cvf myNewFile.jar -C dir .