[Java] Java class run from termianl

In this article, we will learn how to run java program from terminal. First, we open our terminal to check java is already installed or not.

java

Second, we change directory to the src folder which has .java file, we use Demo package and the file PiDemo.java as an example.

cd src
cd demo
ls 

Then, we first compile the .java into a class file (.class)

javac PiDemo.java

At the end, we change directory back to src, then try to run PiDemo from terminal

cd .. 
java Demo/PiDemo I am Steven

I put the reference code in the end, we can check the output is right or wrong.

/src/Demo/PiDemo.java

package Demo;

public class PiDemo {

	public static void main(String[] args) {
		
		for (String elem: args) {
			System.out.println(elem);
		}

		// (1) 10!
		int ans1 = 1;
		for (int x = 0; x < 10; x++) {
			ans1 = ans1 * x;
		}
		System.out.println(ans1);
		
		// (2) 2 ^ 10 = 2 x 2 ... (7 times) ... x 2 = 1024
		double ans2 = 1;
		for (int i = 1; i <= 10; i++) {
			ans2 = ans2 * 2;
		}
		System.out.println(ans2);
		
		// Pi
		double ans3 = 0;
		for (int i = 0; i <= 10000; i++) {
			ans3 += Math.pow(-1, i) / (2 * i + 1);
		}
		ans3 = 4 * ans3;
		System.out.println(ans3);
		
	}

}

Thanks for your patience.