Socket communication in Java enables communication between two endpoints over a network. There are two main types of sockets: TCP sockets and UDP sockets. Let's explain both types with examples: TCP Socket Communication: 1. **Server Side**: - The server creates a `ServerSocket` object to listen for incoming connections on a specific port. - When a client connects, the server accepts the connection and creates a `Socket` object to communicate with the client. - The server reads from and writes to the socket's input and output streams to communicate with the client. import java.io.*; import java.net.*; public class TCPServer { public static void main(String[] args) throws IOException { ServerSocket serverSocket = new ServerSocket(12345); System.out.println("Server started. Waiting for client..."); Socket clientSocket = serverSocket.accept(); ...
Arrays in Java are used to store a collection of elements of the same data type. They provide a convenient way to group related data. Here's an overview of arrays in Java:
Declaration and Initialization:
1. One-Dimensional Array:
- An array with a single row.
// Declaration
dataType[] arrayName;
// Initialization
dataType[] numbers = {1, 2, 3, 4, 5};
2. Multi-Dimensional Array:
- An array with multiple rows and columns.
// Declaration
dataType[][] multiArray;
// Initialization
int[][] matrix = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
Accessing Array Elements:
1. One-Dimensional Array:
- Access elements using their index.
int[] numbers = {10, 20, 30, 40, 50};
int firstElement = numbers[0]; // Accessing the first element.
2. Multi-Dimensional Array:
- Access elements using row and column indices.
int[][] matrix = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
int element = matrix[1][2]; // Accessing the element in the second row, third column.
Array Length:
- The `length` property is used to get the size of an array.
int[] numbers = {1, 2, 3, 4, 5};
int arrayLength = numbers.length; // Gets the length of the array.
Iterating Through Arrays:
1. For Loop:
- Used for iterating through the elements of an array.
int[] numbers = {1, 2, 3, 4, 5};
for (int i = 0; i < numbers.length; i++) {
System.out.println(numbers[i]);
}
2. Enhanced For Loop:
- A concise way to iterate through all elements of an array.
int[] numbers = {1, 2, 3, 4, 5};
for (int num : numbers) {
System.out.println(num);
}
Arrays in Methods:
- Arrays can be passed as parameters to methods.
void printArray(int[] arr) {
for (int num : arr) {
System.out.println(num);
}
}
Array Manipulation:
- Arrays provide methods to sort, search, and manipulate elements.
int[] numbers = {5, 2, 8, 1, 7};
Arrays.sort(numbers); // Sort the array in ascending order.
int index = Arrays.binarySearch(numbers, 2); // Search for the element 2.
Arrays in Java offer flexibility and are an essential part of data structures. They provide an efficient way to organize and manage data in various applications. Understanding how to declare, initialize, and manipulate arrays is fundamental for Java developers.
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