public class L26 {

    /**

     * @param args

     */

    public static void main(String[] args) {

        // TODO Auto-generated method stub

//        double a= 300000;

        double x= 300000.00000000003;//double比较，小数点后有效位

        double y= 300000.000000000003;//主要注意的是double类型直接==/>=/<=的比较，涉及到有效位

        System.out.println(x<=300000);

        System.out.println(y<=300000);

    }

}

/*

 *output:

 *false

  true

 * */
 

public static void main(String[] args) {

        double x= 3.0000000000000003;//double比较，小数点后有效位:17-(整数位)。总有效位为17位

        double y= 30.000000000000003;//17位数字

        double z= 300.00000000000003;

        double w= 3000.0000000000003;

        System.out.println(x==3);

        System.out.println(y==30);

        System.out.println(z==300);

        System.out.println(w==3000);

        System.out.println("--------------------分界线-------------------");

        //小数后都加一个0

        double x1= 3.00000000000000003;//18位数字

        double y1= 30.0000000000000003;

        double z1= 300.000000000000003;

        double w1= 3000.00000000000003;

        System.out.println(x1==3);

        System.out.println(y1==30);

        System.out.println(z1==300);

        System.out.println(w1==3000);

    }

}

/*

output:

false

false

false

false

--------------------分界线-------------------

true

true

true

true

*/