import java.math.BigDecimal;

public class TestGetInt {

    public static void main(String[] args) {

        double i = 2, j = 2.1, k = 2.5, m = 2.9;

        System.out.println("舍掉小数取整:Math.floor(2)=" + (int) Math.floor(i));//

        System.out.println("舍掉小数取整:Math.floor(2.1)=" + (int) Math.floor(j));//

        System.out.println("舍掉小数取整:Math.floor(2.5)=" + (int) Math.floor(k));//

        System.out.println("舍掉小数取整:Math.floor(2.9)=" + (int) Math.floor(m));//

        System.out.println("四舍五入取整:(2)=" + new BigDecimal("2").setScale(0, BigDecimal.ROUND_HALF_UP));//

        System.out.println("四舍五入取整:(2.1)=" + new BigDecimal("2.1").setScale(0, BigDecimal.ROUND_HALF_UP));//

        System.out.println("四舍五入取整:(2.5)=" + new BigDecimal("2.5").setScale(0, BigDecimal.ROUND_HALF_UP));//

        System.out.println("四舍五入取整:(2.9)=" + new BigDecimal("2.9").setScale(0, BigDecimal.ROUND_HALF_UP));//

        System.out.println("凑整:Math.ceil(2)=" + (int) Math.ceil(i));//

        System.out.println("凑整:Math.ceil(2.1)=" + (int) Math.ceil(j));//

        System.out.println("凑整:Math.ceil(2.5)=" + (int) Math.ceil(k));//

        System.out.println("凑整:Math.ceil(2.9)=" + (int) Math.ceil(m));//

        System.out.println("舍掉小数取整:Math.floor(-2)=" + (int) Math.floor(-i));//-2

        System.out.println("舍掉小数取整:Math.floor(-2.1)=" + (int) Math.floor(-j));//-3

        System.out.println("舍掉小数取整:Math.floor(-2.5)=" + (int) Math.floor(-k));//-3

        System.out.println("舍掉小数取整:Math.floor(-2.9)=" + (int) Math.floor(-m));//-3

        System.out.println("四舍五入取整:(-2)=" + new BigDecimal("-2").setScale(0, BigDecimal.ROUND_HALF_UP));//-2

        System.out.println("四舍五入取整:(-2.1)=" + new BigDecimal("-2.1").setScale(0, BigDecimal.ROUND_HALF_UP));//-2

        System.out.println("四舍五入取整:(-2.5)=" + new BigDecimal("-2.5").setScale(0, BigDecimal.ROUND_HALF_UP));//-3

        System.out.println("四舍五入取整:(-2.9)=" + new BigDecimal("-2.9").setScale(0, BigDecimal.ROUND_HALF_UP));//-3

        System.out.println("凑整:Math.ceil(-2)=" + (int) Math.ceil(-i));//-2

        System.out.println("凑整:Math.ceil(-2.1)=" + (int) Math.ceil(-j));//-2

        System.out.println("凑整:Math.ceil(-2.5)=" + (int) Math.ceil(-k));//-2

        System.out.println("凑整:Math.ceil(-2.9)=" + (int) Math.ceil(-m));//-2

    }

}

舍掉小数取整:Math.floor(2)=2

舍掉小数取整:Math.floor(2.1)=2

舍掉小数取整:Math.floor(2.5)=2

舍掉小数取整:Math.floor(2.9)=2

四舍五入取整:(2)=2

四舍五入取整:(2.1)=2

四舍五入取整:(2.5)=3

四舍五入取整:(2.9)=3

凑整:Math.ceil(2)=2

凑整:Math.ceil(2.1)=3

凑整:Math.ceil(2.5)=3

凑整:Math.ceil(2.9)=3

舍掉小数取整:Math.floor(-2)=-2

舍掉小数取整:Math.floor(-2.1)=-3

舍掉小数取整:Math.floor(-2.5)=-3

舍掉小数取整:Math.floor(-2.9)=-3

四舍五入取整:(-2)=-2

四舍五入取整:(-2.1)=-2

四舍五入取整:(-2.5)=-3

四舍五入取整:(-2.9)=-3

凑整:Math.ceil(-2)=-2

凑整:Math.ceil(-2.1)=-2

凑整:Math.ceil(-2.5)=-2

凑整:Math.ceil(-2.9)=-2