How to Install Oracle Java 9 in Ubuntu

In previous post I showed you how to install Oracle Java 8 and 7 but, come on! Oracle Java 9 it’s here and It’s stable in Ubuntu!.

This is the new and easy procedure!

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Predictions for Java 20

Humor pills for programmers!

CuaimaCrypt, a Strong Cryptographic Alternative

Tags

Cryptography, CuaimaCrypt, Secure file, Strong Cryptography

I think CuaimaCrypt is one of best cypher ever designed because it have such a strong algorithm that can resist an quantum computer attacks.

For this reason, I’m currently working to supporting this project; consequently, I share this link with you in order to explain what I’m refer to.

Go to Bolivartech article: CuaimaCrypt, a Strong Cryptographic Alternative

 

Jorge Fernandes is Bachelor in Computer Science experienced in telecommunications, security, banking and programmer since 1984. He works in Valhala Networks focused on high-level decisions about scientific and technological policies and strategies of projects oriented to develop web and standalone applications, as well as smart solutions at mobiles. He always oriented to produce innovator products.

java.lang.OutOfMemoryError and X options

Tags

java.lang.OutOfMemoryError, memory allocation, X options, Xms, Xmx

One common indication of a memory leak is the java.lang.OutOfMemoryError exception. Usually, this error is thrown when there is insufficient space to allocate an object in the Java heap and the garbage collector cannot make space to accommodate a new object, and the heap cannot be expanded further. Also, this error may be thrown when there is insufficient native memory to support the loading of a Java class.

If the java.lang.OutOfMemoryError is due to heap problem, a common solution to this error can be manage the memory allocation pool manually for a Java Virtual Machine by using x options previous to run you application.

The flag Xmx specifies the maximum memory allocation pool for a Java Virtual Machine (JVM), while Xms specifies the initial memory allocation pool.

This means that your JVM will be started with Xms amount of memory and will be able to use a maximum of Xmx amount of memory. For example, starting a JVM like below will start it with 128MB of memory, and will allow the process to use up to 1024MB of memory:

java -Xms128m -Xmx1024m

The memory flag can also be specified in multiple size units, such as kilobytes, megabytes, and so on.

-Xms1024k
-Xmx1024m
-Xmx2g

The default value of Xmx will depends on platform and amount of memory available in the system.

When using these settings, keep in mind that these settings are for the JVM’s heap, and that the JVM can/will use more memory than just the size allocated to the heap. From Oracle’s Documentation:

Note that the JVM uses more memory than just the heap. For example Java methods, thread stacks and native handles are allocated in memory separate from the heap, as well as JVM internal data structures.

Notice: The -X options are subject to change without notice.

 

Jorge Fernandes is Bachelor in Computer Science experienced in telecommunications, security, banking and programmer since 1984. He works in Valhala Networks focused on high-level decisions about scientific and technological policies and strategies of projects oriented to develop web and standalone applications, as well as smart solutions at mobiles. He always oriented to produce innovator products.

Credit Card numbers or IMEI in Java (Luhn Algorithm)

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Credit Card, Credit Card Number, Hans Peter Luhn, IMEI number, Java Luhn, Java Luhn Implementation, Luhn, Luhn Algorithm, Test Credit Card, Test IMEI

Some people ask me about how banks or online retailer know when their credit card number is wrong without a regular request or how their mobile services provider or mobile apps know their smartphone or tablet identification(IMEI) are invalid due to initial system configuration manipulation.

What if I tell you the similarity between this identifications and the java code behind the scene?

It sounds really cool, yeah?

Create a directory if doesn’t exist

If you have to create a directory if doesn’t exist, you can use this code:

Defensive programming

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Defensive programming

I think that one of best coding practices I have learned over time which can help improve the quality of software is the defensive programming; consequently, I share this link with you in order to explain what I’m refer to.

Go to Bolivartech article: Defensive programming to mitigate security breach and unforeseen events

Video: What’s a computer programmer ?

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Bill Gates, computer program, Mark Zuckerberg, Programmer, Steve Jobs

I love this video!!!
It’s a short and beautiful presentation about what’s a computer programmer with short interviews with some personalities like Bill Gates, Mark Zuckerberg, Steve Jobs, etc. What although perhaps you are a programmer I recommend you to see it.

Enjoy!!!

How to Install Oracle Java 8 or 7 in Ubuntu

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oracle java ubuntu install

In some situations you need to run applications developed in Oracle Java over Ubuntu.
If you try to do this with recommended open souce flavors like openjdk-8-jdk and/or openjdk-8-jre sometimes rise up errors or malfunctions.

You can correct this situations by installing original Oracle Java Version 7 or 8 doing this procedure in a terminal:

Some simple Java convertions

People always ask me how to do trivial things like conversions, let’s start
here:

String to Integer:

String stringNumber = "5";
int number = Integer.parseInt(stringNumber);