If there is only 1 class with a main method or if there is a Main-Class defined for the JAR, you can use the following command to run the application.

java -jar app.jar

If you there are multiple classes with main methods in the JAR, you can execute any …

You can install open JDK 8 on Ubuntu 14.04 using the following commands.

sudo add-apt-repository ppa:openjdk-r/ppa
wajig update
wajig install openjdk-8-jdk

For more please refer to https://askubuntu.com/questions/464755/how-to-install-openjdk-8-on-14-04-lts.

See the following code.

String email = "test@test.com";
Pattern p = Pattern.compile(".+@.+\\.[a-z]+");
Matcher m = p.matcher(email);
boolean matchFound = m.matches();
if(matchFound){
    System.out.println("EMAIL OK");
}else{
    System.out.println("EMAIL ERROR");
}

A good summay is here.

String

There are several different ways to copy arrays of object (primitive types) in Java. However, the fastest way seems to be System.arraycopy. This methed is implemented using native code and only performs a shallow copy. Acutally most methods for copying arrays in Java perform shallow copy.

int arr1[] = {0 …