Basic Java Syntax

Question 1

How to run a java program in a console

Answer 1

java <filename></filename>

Question 2

How to compile a java program in a console

Answer 2

javac <filename></filename>

Question 3

Declare a public class

Answer 3

public class <filename> {</filename>

}

Question 4

Invoke a class constructor

Answer 4

<class> <object> = new <class>();
Car ferrari = new Car();
</class></object></class>

Question 5

Print an output

Answer 5

System.out.println(“<output>") ;</output>

Question 6

Declare a public main method

Answer 6

public static void main(String[] args) {

}

Question 7

Single line comment

Answer 7

//

Question 8

Multi line comment

Answer 8

/*

<Comment>
<Comment>
*/
</Comment></Comment>

Question 9

Documentation comment

Answer 9

/**

<documentation>
<documentation>
*/
</documentation></documentation>

Question 10

The name of a Java source file should exactly match what?

Answer 10

The public class

Question 11

Which source file name is correct?

A. GFG.java
B. gfg.java

Answer 11

GFG.java

Question 12

Which print statement is correct?

A. System.out.println(“Alice”);
B. system.out.println(“Alice”);

Answer 12

A. System.out.println(“Alice”);

The “S” in System is capitolized.

Question 13

What is the naming convention for variables and methods?

Answer 13

Lower Camel Case
The first word is always lowercase. Second word is uppercase.

Question 14

What is the naming convention for classses, interfaces, annotations, enums, and records?

Answer 14

Upper Camel Case
The first word is always uppercase. If several words are used to form the name of the class, each inner word’s first letter should be in Uppercase.

Question 15

What is the naming convention for Constants?

Answer 15

Screaming Snake
All letters are Uppercase.

Question 16

How to initialize an array

Answer 16

<Datatype>[] <variable_name> = {value1,value2....

};

ex:
int[] rating = {1,2,3,4,5,6,7,8,9};
</variable_name></Datatype>

Question 17

how to return a value from a method

Answer 17

return <variable_name>;</variable_name>

Question 18

How to create a for loop

Answer 18

for (int i = 0; i < 10; i++) {
code;
}

Question 19

How to declare a two-dimensional loop

Answer 19

int[][] myMatrix;
myMatrix = new int[10][3];

This has 10 rows and 3 columns

Question 20

How do you import the Arraylist?

Answer 20

import java.util.ArrayList;

Question 21

How to declare an array list?

Answer 21

ArrayList <datatype> array_list name = new Arraylist <data_type>(array_size)</data_type></datatype>

ArrayList <String> employees = new ArrayList <String>(5)</String></String>

Question 22

How to add items to an Array List?

Answer 22

Array_name.add(value);

ex:
employees.add(“Jane Eyre”);

Question 23

How to create a for loop for an Array list?

Answer 23

for(data_type counter : Array_name) {

}

ex:
for (String counter : employees) {

}

Question 24

How do you import only the scanner from the java utility class?

Answer 24

import java.util.Scanner;

Question 25

How do you input a value from the scanner function?

Answer 25

Scanner <scanner_name> = new Scanner(System.in);</scanner_name>

Scanner atm_keypad = new Scanner(System.in);