一直以为被零除，应该是会抛出异常的。没想到 double float 不是这样。
前两天，在处理条件分支时，零除数，和一个零被除数，一个非零的被除数，两种除的结果，比较大小时，走了不同的分支。开始时不得其解。后来注意到零除数，于是作了个测试。
结果是，整数类型的会有异常。浮点类型的是不会的。
NaN 和数值进行逻辑比较的结果总是 false 。
public class DivideTest {
/** * @param args */ public static void main(String[] args) { DivideTest dt = new DivideTest(); // 整数 dt.testInt(0, 0); dt.testInt(1, 0); dt.testInt(-1, 0); // 长整形 dt.testLong(0, 0); dt.testLong(1, 0); dt.testLong(-1, 0); // 浮点 dt.testFloat(0, 0); dt.testFloat(1, 0); dt.testFloat(-1, 0); // 双精度 dt.testDouble(0, 0); dt.testDouble(1, 0); dt.testDouble(-1, 0); System.out.println("12>(0.0/0.0) "+(12>(0.0/0.0))); System.out.println("12>(0.1/0.0) "+(12>(0.1/0.0))); System.out.println("12<(0.0/0.0) "+(12<(0.0/0.0))); System.out.println("12<(0.1/0.0) "+(12<(0.1/0.0))); System.out.println("12==(0.0/0.0) "+(12==(0.0/0.0)));
}
private void testInt(int dividend, int divisor){ try { System.out.println("testInt: "+dividend+"/"+divisor+" = "+dividend/divisor); } catch (RuntimeException e) { e.printStackTrace(); } } private void testLong(long dividend, long divisor){ try { System.out.println("testLong: "+dividend+"/"+divisor+" = "+dividend/divisor); } catch (RuntimeException e) { e.printStackTrace(); } } private void testDouble(double dividend, double divisor){ try { System.out.println("testDouble: "+dividend+"/"+divisor+" = "+dividend/divisor); } catch (RuntimeException e) { e.printStackTrace(); } } private void testFloat(float dividend, float divisor){ try { System.out.println("testFloat: "+dividend+"/"+divisor+" = "+dividend/divisor); } catch (RuntimeException e) { e.printStackTrace(); } }
}
java.lang.ArithmeticException: / by zero at test.DivideTest.testInt(DivideTest.java:42) at test.DivideTest.main(DivideTest.java:12)java.lang.ArithmeticException: / by zero at test.DivideTest.testInt(DivideTest.java:42) at test.DivideTest.main(DivideTest.java:13)java.lang.ArithmeticException: / by zero at test.DivideTest.testInt(DivideTest.java:42) at test.DivideTest.main(DivideTest.java:14)java.lang.ArithmeticException: / by zero at test.DivideTest.testLong(DivideTest.java:50) at test.DivideTest.main(DivideTest.java:17)java.lang.ArithmeticException: / by zero at test.DivideTest.testLong(DivideTest.java:50) at test.DivideTest.main(DivideTest.java:18)java.lang.ArithmeticException: / by zero at test.DivideTest.testLong(DivideTest.java:50) at test.DivideTest.main(DivideTest.java:19)testFloat: 0.0/0.0 = NaNtestFloat: 1.0/0.0 = InfinitytestFloat: -1.0/0.0 = -InfinitytestDouble: 0.0/0.0 = NaNtestDouble: 1.0/0.0 = InfinitytestDouble: -1.0/0.0 = -Infinity12>(0.0/0.0) false12>(0.1/0.0) false12<(0.0/0.0) false12<(0.1/0.0) true12==(0.0/0.0) false
