double a = 1.0; double b = 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1 + 0.1; System.out.println("a=" + a + ";b=" + b); System.out.println(a == b); System.out.println(Math.abs(a - b) < 1e-6);