Build the class CalculatorClass.

Author: ImSejin

src/practice/CalculatorClass.java

@@ -0,0 +1,95 @@
+package practice;
+
+import java.util.Scanner;
+
+public class CalculatorClass {
+
+	// 두 매개변수를 더한다
+	private int plus(int x, int y) {
+		return x + y;
+	}
+
+	// 두 매개변수를 뺀다
+	private int minus(int x, int y) {
+		return x - y;
+	}
+
+	// 두 매개변수를 곱한다
+	private int multiply(int x, int y) {
+		return x * y;
+	}
+
+	// 두 매개변수를 나눈다
+	private int divide(int x, int y) {
+		return x / y;
+	}
+
+	// 숫자 3자리마다 ,(comma)로 구분한다
+	public String printComma(long value) {
+
+		String result = "";
+		String temp = String.valueOf(value);
+		int len = temp.length();
+		int header = len % 3;	// 첫번째 콤마 위치
+		char comma = ',';
+		
+		// comma로 구분할 필요가 없을 때
+		if (len < 4) {
+			return temp;
+		}
+		
+		// len이 3의 배수라면 처음의 comma를 찍지 않는다
+		if (header != 0) {
+			result += temp.substring(0, header);
+			result += comma;
+		}
+		
+		// 3자리마다 구분한다
+		result += temp.substring(header, header + 3);
+		for (int i=3; header+i+3<=len; i=i+3) {
+			result += comma;
+			result += temp.substring(header + i, header + i + 3);
+		}
+		
+		return result;
+	}
+
+	// 계산을 수행한다
+	public void calculate() {
+
+		Scanner scanner = new Scanner(System.in);
+		CalculatorClass cal = new CalculatorClass();
+
+		String func = "";
+		int x;
+		int y;
+		int result = 0;
+		boolean isOperator = false;
+
+		// 사칙연산기호가 올바른지 검사한다
+		while ( !isOperator ){
+			System.out.print("사칙연산을 선택하세요.\n> ");
+			func = scanner.nextLine();
+
+			isOperator = func.equals("+") || func.equals("-") || func.equals("*") || func.equals("/");
+		}
+
+		// 계산할 매개변수를 입력 받는다
+		System.out.print("x값을 입력하세요.\n> ");
+		x = scanner.nextInt();
+		System.out.print("y값을 입력하세요.\n> ");
+		y = scanner.nextInt();
+
+		// 입력받은 계산을 수행한다
+		switch (func) {
+			case "+" : result = cal.plus(x, y); 	break;
+			case "-" : result = cal.minus(x, y); 	break;
+			case "*" : result = cal.multiply(x, y); break;
+			case "/" : result = cal.divide(x, y); 	break;
+		}
+
+		System.out.println("result: " + result);
+		scanner.close();
+	}
+	
+}

src/practice/MainClass.java

@@ -0,0 +1,28 @@
+package practice;
+
+import static java.lang.System.out;
+
+//import java.math.BigInteger;
+//import java.math.BigDecimal;
+import java.text.DecimalFormat;
+
+public class MainClass {
+
+	public static void main(String[] args) {
+//		BigInteger num = new BigInteger("123456789012345678901234567890");
+//		BigDecimal number = new BigDecimal(num);
+		CalculatorClass cal = new CalculatorClass();
+		long l = (long)Math.pow(2, 62.999999999999997);
+		String result = cal.printComma(l);
+		
+		out.println(result);
+		
+		DecimalFormat formatter = new DecimalFormat("#,###.00");
+		out.println(formatter.format(l));
+		
+		out.printf("%,d", l);
+		out.println();
+		out.println(String.format("%,d", l));
+	}
+
+}