Java BigDecimal class overview and construction method

BigDecimal class

 

• Since when in operation, float type and double easily lose precision, presentation cases. So, in order to accurately represent, floating-point calculation, the Java offers BigDecimal
• BigDecimal class overview

Immutable, arbitrary-precision signed decimal numbers .

• The method of construction (here speak only one)

public BigDecimal(String val)

 

Test, previously unused: Accuracy is easy to lose

package cn.wen;

public class BigDecimalDemo {
	public static void main(String[] args) {
		System.out.println(0.09 + 0.01);
		System.out.println(1.0 - 0.32);
		System.out.println(1.015 * 100);
		System.out.println(1.301 / 100);

		System.out.println(1.0 - 0.12);
	}
}

0.09999999999999999
0.6799999999999999
101.49999999999999
0.013009999999999999
0.88

• BigDecimal class member method

public BigDecimal add( BigDecimal augend )：加

public BigDecimal subtract( BigDecimal subtrahend )：减

public BigDecimal multiply( BigDecimal multiplicand )：乘

public BigDecimal divide( BigDecimal divisor )： 除

public BigDecimal Divide ( BigDecimal divisor, int Scale, int roundingMode): business, several decimal places, how to get homes

 

package cn.wen_02;

import java.math.BigDecimal;

public class BigDecimalDemo {
	public static void main(String[] args) {
		// System.out.println(0.09 + 0.01);
		// System.out.println(1.0 - 0.32);
		// System.out.println(1.015 * 100);
		// System.out.println(1.301 / 100);

		BigDecimal bd1 = new BigDecimal("0.09");
		BigDecimal bd2 = new BigDecimal("0.01");
		System.out.println("add:" + bd1.add(bd2));
		System.out.println("-------------------");

		BigDecimal bd3 = new BigDecimal("1.0");
		BigDecimal bd4 = new BigDecimal("0.32");
		System.out.println("subtract:" + bd3.subtract(bd4));
		System.out.println("-------------------");

		BigDecimal bd5 = new BigDecimal("1.015");
		BigDecimal bd6 = new BigDecimal("100");
		System.out.println("multiply:" + bd5.multiply(bd6));
		System.out.println("-------------------");

		BigDecimal bd7 = new BigDecimal("1.301");
		BigDecimal bd8 = new BigDecimal("100");
		System.out.println("divide:" + bd7.divide(bd8));
		System.out.println("divide:"
				+ bd7.divide(bd8, 3, BigDecimal.ROUND_HALF_UP));    //小数后三位
		System.out.println("divide:"
				+ bd7.divide(bd8, 8, BigDecimal.ROUND_HALF_UP));    //小数后八位
	}
}