Java methods list with examples

Java methods list with examples

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Java provides a wide range of built-in and user-defined methods that can be used to perform various tasks. Here are some common Java method types along with their examples:

1. Void Methods:

These methods do not return any value.

Example:

public static void printHello() {
System.out.println("Hello");
}

To call this method, you would use printHello();

2. Return-Type Methods:

These methods return a value of a specified type.

Example (returns an integer):

public static int getSum(int a, int b) {
return a + b;
}

To call this method and use the returned value, you would do something like:

int result = getSum(2, 3);
System.out.println("The sum is " + result);

3. Constructor Methods:

These methods are used to initialize objects when they are created.

Example (constructs a new Person object):

public class Person {
private String name;
public Person(String name) {
this.name = name;
}
}
Person p = new Person("John");

4. Static Methods:

These methods can be called without creating an instance of the class.

Example (prints "Hello" to the console):

public class Greeting {
public static void printHello() {
System.out.println("Hello");
}
}
Greeting.printHello(); // Output: Hello

5. Instance Methods:

These methods must be called on an instance of the class.

Example (calculates the area of a rectangle):

public class Rectangle {
private int width;
private int height;
public Rectangle(int w, int h) {
width = w;
height = h;
}
public double getArea() {
return width * height;
}
}
Rectangle r = new Rectangle(5, 3);
double area = r.getArea(); // Output: 15.0

6. Abstract Methods:

These methods must be implemented by any subclass.

Example (abstract method in an Animal class):

public abstract class Animal {
public abstract void makeSound();
}
public class Dog extends Animal {
@Override
public void makeSound() {
System.out.println("Woof!");
}
}
Dog d = new Dog();
d.makeSound(); // Output: Woof!

7. Final Methods:

These methods cannot be overridden by subclasses.

Example (final method in a class):

public class MyClass {
public final void finalize() {
System.out.println("Object is being finalized");
}
}

These are just a few examples of the many types of Java methods you can create. Remember to always follow proper naming conventions and usage guidelines when writing your own methods!

What are the list interface methods in Java?

The list of interface methods in Java includes:

public boolean add(E e);

public boolean addAll(Collection c);

public void clear();

public boolean contains(Object o);

public boolean containsAll(Collection c);

public boolean equals(Object o);

public int hashCode();

public boolean isEmpty();

public Iterator iterator();

public boolean remove(Object o);

public boolean removeAll(Collection c);

public boolean retainAll(Collection c);

public void set(int index, E element);

public int size();

public  T[] toArray(T[] a);

public String toString();

public Object[] toArray();

These are the most common interface methods in Java for working with collections.