Java programming basics practice-switch statement

Is it easy to write the program I made when I was a newcomer now in my second year, or have I forgotten it? I thought, so I made it.

Conclusion

• You can make something that works for the time being (although it's almost thanks to Eclipse)
• I wonder what I didn't wonder when I was a newcomer

problem

• Source file name "Check22.java"
• 2 Enter the number (integer) and calculation method (1 character).
• Performs the specified calculation and outputs the calculation result
• Use the switch statement to branch the process according to the calculation method.
• For other details, please refer to the following execution results.

Please enter the first number>
10
Please enter the second number>
3
Please select the calculation method>
(a)Addition
(b)Subtraction
(c)Multiply
(b)division
d
The answer is 3

Implementation

I made it as follows.

Check22.java

package practice;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Check22 {

	public static void main(String[] args) {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

		String line = null;
		int num1 = 0;
		int num2 = 0;
		try {
			System.out.println("Please enter the first number");
			line = reader.readLine();
			num1 = Integer.parseInt(line);
			System.out.println("Please enter the second number");
			line = reader.readLine();
			num2 = Integer.parseInt(line);

			System.out.println("Please select the calculation method");
			System.out.println("(a)Addition");
			System.out.println("(b)Subtraction");
			System.out.println("(c)Multiply");
			System.out.println("(d)division");

			line = reader.readLine();
			if (!( line.equals("a")) && !( line.equals("b") )&& !( line.equals("c") )&& !( line.equals("d"))) {
				System.out.println("a,b,c,Please enter one of d");
			}else {
				String symbol = line;
				int answer = calc(num1,num2,symbol);
				System.out.println("The answer is" + answer + "is.");
			}
		}catch(NumberFormatException e) {
			System.out.println("Please enter a number");
		}catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static int calc(int num1, int num2, String symbol) {
		int result;
		switch(symbol) {
		case "a":
			result = num1 + num2;
			break;
		case "b":
			result = num1 - num2;
			break;
		case "c":
			result = num1 * num2;
			break;
		default:
			result = num1 / num2;
			break;
		}
		return result;
	}

}

Question

• If you do not write break in the switch statement of the calc method, all processing will run. -At first, I didn't write break; and even if I entered a, all the cases were processed and the result was not as expected. When I entered case "a" :, I thought that only a would be processed, but I knew that the processing would not be completed until break; came. (Last year, I wrote break; for the time being, so I think I wrote it with the intention of adding break;)
• If static is not added to the calc method, an error will occur (Error content: Non-static method calc (int, int, string) of type Check22 cannot be statically referenced) -Since it is a method in the same class, you can refer to it without adding static! I was thinking. The error content is the same, but I found out that methods with static cannot use non-static methods directly. Since static methods are managed in places that are not related to instances, even if you try to refer to them from non-static methods, you will not be able to determine "where is this instance method?", So a compile error will occur. Yeah. I feel like I understand it somehow. (But the main method is a static method, so if you want to refer to a method from there, I feel that you have to add static to all methods, but the question of what to do is unsolved.)

Impressions

• Maybe I didn't think about exception handling in the first year
• I'm not good at thinking about variable names and method names