java.lang.System.arraycopy() method offers a convenient method to copy array elements from one array to another.

System.arraycopy(Object source_array, int source_position,

Object destination_array, int destination_position, number_of_elements)

System.arraycopy() takes five parameters.

First parameter specifies the source_array from where the elements need to be copied.

Second parameter is the position(index) value of the source array from what index array is to be copied.

Third parameter specifies the destination array to which array the values need to be copied. Fourth parameter specifies the destination array starting index.

Fifth parameter specifies the numberOfElements need to be copied from source array to destination array.

Check out your understanding with below example.

import java.io.*;

class Student

{

int b[] = new int[5];

Student(int[] a)

{

System.arraycopy(a,0,b,0,5);

}

void Display()

{

for(int i=0;i<5;i++)

{

System.out.println(b[i]);

}

}

}

class StudentClass

{

public static void main(String [] args) throws IOException

{

DataInputStream dis = new DataInputStream(System.in);

int a[] = new int[5];

System.out.print(”Enter marks : “);

for(int i=0;i<5;i++)

{

a[i]=Integer.parseInt(dis.readLine());

}

Student st = new Student(a);

st.Display();

}

}

Static block/variables/methods are very powerful in java.

When we say static it is static throughout the application. If you declare a static variable in a stand-alone application, the life of the variable will be throughout the end of the application but in the case of the web application, static variable  has life till the web server is stopped.

Static variables are executed at first the program runs. Next the static block is executed. Static methods are executed when a call is raised.

Note: Static methods can call only static methods. To call non-static methods instance of the class should be created

Refer below code for better understanding

class UseStatic

{

static int a=3;

static int b;

static void meth(int x)

{

System.out.println(”x: “+x);

System.out.println(”a: “+a);

System.out.println(”b: “+b);

}

static

{

System.out.println(”static block initialized: “);

b=a*4;

}

public static void main(String [] args)

{

meth(42);

}

}