All Questions

I have the following code from the java oracle documentation:

public class LocalClassExample {

    static String regularExpression = "[^0-9]";

    public static void validatePhoneNumber(
        String phoneNumber1, String phoneNumber2) {

        final int numberLength = 10;

        // Valid in JDK 8 and later:

        // int numberLength = 10;

        class PhoneNumber {

            String formattedPhoneNumber = null;

            PhoneNumber(String phoneNumber){
                // numberLength = 7;
                String currentNumber = phoneNumber.replaceAll(
                  regularExpression, "");
                if (currentNumber.length() == numberLength)
                    formattedPhoneNumber = currentNumber;
                else
                    formattedPhoneNumber = null;
            }

            public String getNumber() {
                return formattedPhoneNumber;
            }

            // Valid in JDK 8 and later:

// public void printOriginalNumbers() {
// System.out.println("Original numbers are " + phoneNumber1 +
// " and " + phoneNumber2);
// }
        }

        PhoneNumber myNumber1 = new PhoneNumber(phoneNumber1);
        PhoneNumber myNumber2 = new PhoneNumber(phoneNumber2);

        // Valid in JDK 8 and later:

// myNumber1.printOriginalNumbers();

        if (myNumber1.getNumber() == null)
            System.out.println("First number is invalid");
        else
            System.out.println("First number is " + myNumber1.getNumber());
        if (myNumber2.getNumber() == null)
            System.out.println("Second number is invalid");
        else
            System.out.println("Second number is " + myNumber2.getNumber());

    }

    public static void main(String... args) {
        validatePhoneNumber("123-456-7890", "456-7890");
    }
}

In this part of the official java documentation

Local classes are classes that are defined in a block, which is a group of zero or more statements between balanced braces. You typically find local classes defined in the body of a method.

I understand that a local class are classes defined in a block, etc., but I don't understand their purpose in general.

• What could you use them for?
• Are they similar to java anonymous classes or are they different?

In PHP there are several ways to add files into others using:

• require()
• require_once()
• include()
• include_once()

But is there any difference between them?

Are there specific cases where it is better to use one or the other?

The objective of the question is to have a clear idea about whether in some cases it is convenient to use one or the other, to have a more optimized code taking into account the consumption of resources or other criteria, for this reason, it is convenient that in the answer it is indicated if the use of one or the other affects to a greater or lesser degree the amount of memory that is consumed or other important details.

For example if I use:

printf("ó á");

The result obtained in the console is:

¾ ß

Where 3/4 represents ó and ß represents á

I am doing a login .Net which before and after each process will fill a stringwith the message:

"proceso x realizado \n"
"proceso y saltado \n" //porque o se realiza x o y 
"proceso a fallo al sumar \n"
"proceso n [...] \n"

Each message is added to stringafter each process with all the messages it has.

As it appears in the title there are several ways to create one stringof this type.

To which my question is, which of the ways to create a stringis the one that consumes less resources or is more efficient.

It should be noted that the stringending will have at least 25 lines

What is the difference between the following lines:

if not x == 'val':

Y

if x != 'val':

Is there a way to check if one is more efficient than the other?

Or, maybe the following block would be better:

if x == 'val':
    pass
else: