if (x1.isInfinite()) System.out.println("x1无穷大！");

　　if (x2.isInfinite()) System.out.println("x2无穷大！");

　　if (x3.isNaN()) System.out.println("x3非数字！");

　　if (x4.isNaN()) System.out.println("x4非数字！");

　　if (x1 == Double.POSITIVE_INFINITY) System.out.println("x1 = Double.POSITIVE_INFINITY");

　　if (x2 == Double.NEGATIVE_INFINITY) System.out.println("x1 = Double.NEGATIVE_INFINITY");

　　if (x3 == Double.NaN) System.out.println("x3 = Double.NaN");

　　if (x4 == Double.NaN) System.out.println("x4 = -Double.NaN");

　　System.out.println("------------Float型----------");

　　Float y1 = div(2.3f, 0.0f);

　　Float y2 = div(2.3f, -0.0f);

　　Float y3 = div(0.0f, 0.0f);

　　Float y4 = div(0.0f, -0.0f);

　　Float y5 = div(0.0f, -0.1f);

　　System.out.println("------------比较测试----------");

　　Float a = 99999999999999999999999999999999999999f;

　　Float b = 0.000000000000000000000000000000000000000000001f;

　　Float t = a / b;

　　System.out.println(t);

　　System.out.println(Float.MAX_VALUE);

　　if (t >= Float.MAX_VALUE) {

　　System.out.println("a/b的商已经超过了Float的最大值了！");

　　}

　　}

　　public static Double div(double a, double b) {

　　double x = a / b;

　　System.out.println(a + "/" + b + " = " + x);

　　return x;

　　}

　　public static Float div(float a, float b) {

　　float x = a / b;

　　System.out.println(a + "/" + b + " = " + x);

　　return x;

　　}

　　}