double类型相减结果误差的解决办法

public class DBConnectionManager {
public static void main(String[] args) {
double a1 = 1.0;
double a2 = 2.2;

//使用一下3句代码
double a3 = a2-a1;
String formatString = "###.######";
java.text.DecimalFormat decimalformat = new java.text.DecimalFormat(formatString);
System.out.println(decimalformat.format(a3));

//System.out.println(a3);
//double s = 1.2345;
//double d = 123.4325;

double s = 1.42;
double d = 123.23;
double o = 0;
o = java.lang.Math.abs(d - s);
System.out.println(o);

}
}