Java Basics 104 - Operator Precedence

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Java Basics 104 – Operator Precedence

STEPS

1) Browse http://ideone.com/1gau2Z 

http://ideone.com/1gau2Z 

2) Three numbers operation

Change line no. 13 to:

int first_number, second_number, third_number, answer;

Change line no.14-15 to:

first_number = 100; second_number = 75; third_number = 25;

Change line no. 16 to:

answer = first_number - second_number + third_number;

Change line no.18 to:

System.out.println("Total = " + answer );

Outcome:

http://ideone.com/Uwh99a 

3) Three numbers operation with bracket 1

Change line no. 17 to:

answer = (first_number - second_number) + third_number;

Outcome:

http://ideone.com/pvedQe 

4) Three numbers operation with bracket 2

Change line no. 17 to:

answer = first_number - (second_number + third_number);

Outcome:

http://ideone.com/qxudcb 

5) Three numbers operation with + and *

Change line no. 17 to:

answer = first_number + second_number * third_number;

Outcome:

http://ideone.com/UZPD18 

The following codes also leads to the same outcome:

answer = first_number + (second_number * third_number);

Outcome: http://ideone.com/3AQzNT 

Change the position of the brackets as follows. What would be the outcome?

answer = (first_number + second_number) * third_number;

Outcome: http://ideone.com/j0jI5j 

6) Three numbers operation with () and /

Change line no. 17 as follows. What is the outcome?

answer = first_number + second_number / third_number;

Outcome: http://ideone.com/qzwpyM 

Change line no. 17 as follows. What is the outcome?

answer = (first_number + second_number) / third_number;

Outcome: http://ideone.com/IiGGKn 

LESSONS:

Here's a list on Operator Precedence

• Multiply and Divide - Treated equally, but have priority over Addition and Subtraction
• Add and Subtract - Treated equally but have a lower priority than multiplication and division

So if you think Java is giving you the wrong answer, remember that Operator Precedence is important, and add some round brackets.

REFERENCE

 http://www.homeandlearn.co.uk/java/operator_precedence.html 

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Java Basics 103 - Short and Float Variables

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Java Basics 103 – Short and Float Variables

STEPS

1) Browse http://ideone.com/O5GIga 

http://ideone.com/O5GIga 

2) Change the variables properties to Float Data Types.

Change line no.13 to:

float first_number, second_number, answer;

Change line no.14, 15 to:

first_number = 10.5f; second_number = 20.8f;

Outcome:

http://ideone.com/NV31e4 

3) Change the Operator to Division

Change the operator in line no.16 from “+” to “/”.

Outcome:

http://ideone.com/uvsGVV 

4) Double Variables

Change the Data Type for variables in line no.13 to Double.

Outcome:

http://ideone.com/S4VYLO 

Lessons:

When you use Float Data Type, the answer was 0.5048077. Java has taken the first 6 numbers after the point and then rounded up the rest.

However, the double variable type can hold more numbers than float. (Double is a 64 bit number and float is only 32 bit.)

REFERENCE

http://www.homeandlearn.co.uk/java/short_float_variables.html 

 

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Java Basics 102 - Double Variables

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Java Basics 102 – Double Variables

STEPS

1) Browse http://ideone.com/1gau2Z 

 

http://ideone.com/1gau2Z 

2) Change the variables properties to Double Data Types.

Change line no.13 to:

double first_number, second_number, answer;

Change line no.14, 15 to:

first_number = 10.5; second_number = 20.8;

Outcome:

http://ideone.com/O5GIga 

REFERENCE

http://www.homeandlearn.co.uk/java/double_variables.html 

 

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Java Basics 101- Java Variables

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ATTENTION! An updated version of this article is available at http://javadevsteps.blogspot.com/2014/08/ideone-java-basics-101-getting-started.html

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Java Basics 101 – Variables

STEPS

1) Browse  http://ideone.com/VOBd7C 

IdeOne.com is an Online Compiler that allows Java Code to be written and compiled online.

We would be able to learn a lot from here without even have to install Java Development Kit to our PC.

http://ideone.com/VOBd7C 

2) Understanding Java Code Structure

2-1) Package Name

2-2) Import Declarations

2-3) Class Declaration

2-4) Method Declaration

2-5) User Instructions

http://ideone.com/VOBd7C 

3) Basic Instructions – Variable Declaration and Print Statement

As a quick start, ignore Package Name, Import Declarations and Class Declarations first.

Let’s look at basic program instructions first (Line no. 12).

Replace line No.12 with the following codes:

int first_number; System.out.println("My First Project");

Outcome:

http://ideone.com/wA5W3n 

Lesson:

- Variable is identified by its name and data type.

- Printing statement returns value to user. (in the above example it is a string)

4) Variable Assignment

public static void main(String[ ] args) { int first_number; first_number = 10; System.out.println("My First Project"); }

Outcome:

http://ideone.com/QtA0Lv 

Lessons:

- Variable can store value; a process called assignment gives a value for variable to store.

5) Print Variable Value

Change line no. 15 to the following:

System.out.println( "First number = " + first_number );

Outcome:

http://ideone.com/nKqQEw 

Lessons:

- We can combine string with variable.

- We join string and variable with join operator “+”; a process called Concatenation.

6) Variables and Data Operation

Change line no. 13 to the following:

int first_number, second_number, answer;

Change line no. 14 to the following:

first_number = 10; second_number = 20; answer = first_number + second_number;

Change line no.15 to the following

System.out.println("Addition Total = " + answer );

Outcome:

http://ideone.com/1gau2Z 

Lessons:

- You can declare many variables of the same daya type in a single statement.

- Number operation is similar to that of Mathematics.

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Moderated from: http://www.homeandlearn.co.uk/java/java_int_variables.html
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JAVA SE INSTALL NETBEANS IDE 7-3

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JAVA SE: INSTALL NETBEANS IDE 7.3

STEPS

1) Install Java SDK

2) Download NetBeans 7.3

3) Install NetBeans 7.3)

4) Running NetBeans for the first time.

STEPS

1) Install Java SDK

e.g jdk-7u25-windows-i586.exe

Check that java has been installed correctly by typing “java –version” in Command Window.

2) Download NetBeans 7.3

Get information from https://netbeans.org/community/releases/73/index.html 

Download from https://netbeans.org/downloads/7.3/start.html?platform=windows&lang=en&option=javase 

e.g. Download netbeans-7.3-javase-windows.exe

3) Install NetBeans 7.3)

3-1) Run the installer netbeans-7.3-javase-windows.exe

3-2) Welcome Screen.

3-3) Accept the terms.

3-4) Option to install JUnit.

3-5) Choose installation folder.

3-6) Option to check for update.

3-7) Wait for installation process to complete.

3-8) Installation done.

4) Running NetBeans for the first time.

4-1) Double-click the NetBeans IDE icon on the desktop.

4-2) NetBeans Main Application window appears on screen.

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