Example1Chapter3Level2

package com.gmail.kudr641;

import java.util.Scanner;

public class Example1Chapter3Level2 {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		System.out.println("Input number:");
		int size = scanner.nextInt();
		scanner.close();
		String str = "";

		for (int i = 0; i < 2 * size - 1; i++) {
			if (i < size) {
				str += "*";
			} else {
				str = str.substring(0, str.length() - 1);
			}
			System.out.println(str);
		}
	}
}

Example2Chapter3Level2

package com.gmail.kudr641;

public class Example2Chapter3Level2 {

	public static void main(String[] args) {

		for (int i = 2; i <= 100; i += 1) {
			boolean prime = true;

			for (int j = i - 1; j > 1; j--) {
				if (i % j == 0) {
					prime = false;
				}
			}
			if (prime == true) {
				System.out.println(i);
			}
		}
	}
}

Example3Chapter3Level2

package com.gmail.kudr641;

import java.util.Scanner;

public class Example3Chapter3Level2 {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);

		System.out.println("Input size:");
		int size = scanner.nextInt();

		scanner.close();

		String str = "";

		if (size % 2 == 0) {
			System.out.println("Number pair");
		} else {

			for (int i = 0; i < size; i++) {
				str += "*";
			}

			for (int i = 0; i < size; i++) {
				System.out.println(str);
				if (i < size / 2) {

					str = " " + str;
					str = str.substring(0, str.length() - 2);
				}
				if (i >= size / 2) {
					str += "**";
					str = str.substring(1, str.length());
				}
			}
		}
	}
}