Java is a general-purpose programming language that is widely used for developing desktop, web, and mobile applications. Here’s a quick overview of its unique features and some code blocks for common tasks.
Declare variables using the data type followed by the variable name. Java is a statically typed language, so the data type of a variable cannot be changed after it is declared.
int x = 10;
char c = 'a';
double d = 3.14;
Functions in Java are declared using the public static keywords. They can take parameters and return values.
public static int add(int a, int b) {
return a + b;
}
Java supports for, while, and do-while loops for iterating over arrays or performing a task a certain number of times.
int[] numbers = {1, 2, 3, 4, 5};
for (int i = 0; i < 5; i++) {
System.out.println(numbers[i]);
}
int i = 0;
while (i < 5) {
System.out.println(numbers[i]);
i++;
}
i = 0;
do {
System.out.println(numbers[i]);
i++;
} while (i < 5);
Use if statements to execute code based on a condition. else if and else statements can be used to handle multiple conditions.
int x = 10;
if (x > 0) {
System.out.println("x is positive");
} else if (x < 0) {
System.out.println("x is negative");
} else {
System.out.println("x is zero");
}
Java provides built-in support for file manipulation, including reading and writing files, and interacting with the file system.
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
public class Main {
public static void main(String[] args) {
File file = new File("/path/to/file.txt");
try {
String contents = new String(Files.readAllBytes(Paths.get(file.getAbsolutePath())));
System.out.println(contents);
Files.write(Paths.get(file.getAbsolutePath()), "New contents".getBytes());
if (file.delete()) {
System.out.println("File deleted successfully");
} else {
System.out.println("Error deleting file");
}
} catch (IOException e) {
System.out.println("An error occurred");
e.printStackTrace();
}
}
}
Here are some resources to help you learn more about Java: