[자바(Java)] BigInteger , BigDecimal

//BigInteger

타입	범위
int	-2,147,483,648 ~ 2,147,483,647
long	-9,223,372,036,854,775,808 ~9,223,372,036,854,775,807
BigInteger	무한(∞)

- 숫자가 지나치게  커서 int나 long의 범위를 벗어날 땐 BigInteger를 사용할 수 있다.

- import java.math.BigInteger;

- 생성 및 선언

BigInteger 변수명 = new BigInteger(원하는 숫자-문자열의 형태로);

BigInteger num1 = new BigInteger("10");

※ BigInteger를 생성할 때 생성자 안에 꼭 문자열의 형태로 숫자를 입력해야 한다.

- 더하기

num1.add(num2);

- 빼기

num1.subtract(num2);

- 곱하기

num1.multiply(num2);

- 나누기

num1.divide(num2);


- 최대공약수

num1.gcd(num2);

- 결과를 int로 변환

num.intValue();

---

import java.math.BigInteger;

public class Ex16 {
	public static void main(String[] args) {
		BigInteger num1 = new BigInteger("10");
		BigInteger num2 = new BigInteger("5");
		
		System.out.println("10 + 5 = " + num1.add(num2));
		System.out.println("10 - 5 = " + num1.subtract(num2));
		System.out.println("10 * 5 = " + num1.multiply(num2));
		System.out.println("10 / 2 = " + num1.divide(num2) + "\n");
		
		BigInteger num3 = new BigInteger("24");
		num3 = num3.add(new BigInteger("6"));
		System.out.println("24 + 6 = " + num3);	
	}
}

 

import java.math.BigInteger;

public class Ex26 {
	public static void main(String[] args) {

		int a = 12;
		int b = 21;

		int answer = 1;

		BigInteger numerator = BigInteger.valueOf(a);
		BigInteger denominator = BigInteger.valueOf(b);
		BigInteger gcd_ = numerator.gcd(denominator);

		int gcd = gcd_.intValue();

		System.out.println(gcd);
	}
}

---

** BigDecimal 클래스를 이용해서 소수도 활용할 수 있다.

package com.sorrel012.primitive.datatypes;

import java.math.BigDecimal;

public class SimpleInterestCalculator {

	private BigDecimal principal;
	private BigDecimal interest;

	public SimpleInterestCalculator(String principal, String interest) {
		this.principal = new BigDecimal(principal);
		this.interest = new BigDecimal(interest).divide(new BigDecimal(100));
	}

	public BigDecimal calculateTotalValue(int noOfYears) {
		BigDecimal totalValue = principal.add(principal.multiply(interest).multiply(new BigDecimal(noOfYears)));
		return totalValue;
	}

}

 

package com.sorrel012.primitive.datatypes;

import java.math.BigDecimal;

public class SimpleInterestCalculatorRunner {
	public static void main(String[] args) {
		SimpleInterestCalculator calculator = new SimpleInterestCalculator("4500.00", "7.5");
		BigDecimal totalValue = calculator.calculateTotalValue(5);
		System.out.println(totalValue);
	}

}

---

package com.sorreo012.arrays;

import java.math.BigDecimal;

public class StudentRunner {

    public static void main(String[] args) {

	int[] marks = {97, 98, 100};

	Student student = new Student("Hanee", marks);

	int number = student.getNumberOfMarks();
	int sum = student.getTotalSumOfMarks();
	int maxMark = student.getMaxMark();
	int minMark = student.getMinMark();
	BigDecimal average = student.getAverageMarks();

	System.out.println("number of marks : " + number);
	System.out.println("sum of marks : " + sum);
	System.out.println("maximum of marks : " + maxMark);
	System.out.println("minimum of marks : " + minMark);
	System.out.println("average of marks : " + average);

    } //main

}

 

package com.sorreo012.arrays;

import java.math.BigDecimal;
import java.math.RoundingMode;

public class Student {

    private String name;
    private int[] marks;

    public Student(String name, int[] marks) {
	this.name = name;
	this.marks = marks;
    }

    public int getNumberOfMarks() {
	return marks.length;
    } //getNumberOfMarks

    public int getTotalSumOfMarks() {
	int sum = 0;
	for(int mark : marks) {
	    sum += mark;
	}
	return sum;
    } //getTotalSumOfMarks

    public int getMaxMark() {
	int max = Integer.MIN_VALUE;
	for(int mark : marks) {
	    if(mark > max) {
		max = mark;
	    }
	}
	return max;
    } //getMaxMark

    public int getMinMark() {
	int min = Integer.MAX_VALUE;
	for(int mark : marks) {
	    if(mark < min) {
		min = mark;
	    }
	}
	return min;
    } //getMinMark

    public BigDecimal getAverageMarks() {
	int sum = getTotalSumOfMarks();
	int number = getNumberOfMarks();

	return new BigDecimal(sum).divide(new BigDecimal(number), 3, RoundingMode.UP);
    }