java中System.out.println(1.0/0)会输出什么

package erdan.demo;public class TestDouble {    public static void main(String[] args) {         System.out.println(1.0 / 0);    }}

为什么呢？

/**   * 一个常数，保持类型的正无穷大  */public static final double POSITIVE_INFINITY = 1.0 / 0.0;/** * 一个常数，保持类型的负无穷大 */public static final double NEGATIVE_INFINITY = -1.0 / 0.0;/**   * 一个常数,非数值类型 */public static final double NaN = 0.0d / 0.0;

Double 正无穷 = 1.0 / 0;Double 负无穷 = -1.0 / 0;
System.out.println("正无穷:" + 正无穷);System.out.println("负无穷:" + 负无穷);Double 非数值 = 0.0 / 0;System.out.println("非数值 0.0/0 ->" + 非数值);

              正无穷:Infinity          负无穷:-Infinity          非数值 0.0/0 ->NaN

public static void testFloatInfinity() {     Float infFloat = Float.POSITIVE_INFINITY;          Double infDouble = Double.POSITIVE_INFINITY;          System.out.println("infFloat + 5 = " + (infFloat + 5));          System.out.println("infFloat - infDouble = " + (infFloat - infDouble));          System.out.println("infFloat * -1 = " + (infFloat * -1));}

infFloat + 5 = InfinityinfFloat - infDouble = NaNinfFloat * -1 = -Infinity

public static void checkFloatInfinity() {    Double 正无穷 = 1.0 / 0;     Double 负无穷 = -1.0 / 0;     Double 非数值 = 0.0 / 0;     System.out.println("判断正无穷: " + Double.isInfinite(正无穷));     System.out.println("判断负无穷: " + (Double.NEGATIVE_INFINITY == 负无穷));     System.out.println("判断非数值(==): " + (Double.NaN == 非数值));     System.out.println("判断非数值(isNaN):  " + Double.isNaN(非数值));}

              判断正无穷: true          判断负无穷: true          判断非数值(==): false          判断非数值(isNaN):  true