jls

I was looking at the JLS Chapter 19 grammar trying to figure out how a simple field access is parsed: obj.field It looks to me like the first variant of the FieldAccess production is probably involved FieldAccess : Primary . Identifier super . Identifier TypeName . super . Identifier and that Primary should then be involved in parsing the obj part. Primary doesn't seem to be involved with parsing a simple reference like ExpressionName . That seems to be reached via PostfixExpression . PostfixExpression : Primary ExpressionName PostIncrementExpression PostDecrementExpression and, AFAICT,

案例为20行一页。 创建存储过程进行处理： BEGIN # 已查询记录数、每页记录数、需增加记录数 DECLARE jls,myjls,zjjls int; # DROP TEMPORARY TABLE if EXISTS t1; #将查询后的数据放入临时表 CREATE TEMPORARY TABLE t1 SELECT zd1,zd2 FROM `table1` LIMIT 35; SET myjls=20; SELECT COUNT(1) INTO jls FROM t1; #需增加的记录数计算 SET zjjls=jls mod myjls; if zjjls<>0 THEN SET zjjls=myjls-zjjls; end if; #循环补空行 while zjjls<>0 DO INSERT into t1 SELECT null,null; #SELECT zjjls; SET zjjls=zjjls-1; END while; #输出 SELECT * from t1; END 来源： CSDN 作者： andywan 链接： https://blog.csdn.net/andywan/article/details/52387364

With parameterized types in Java, how do the rules that check if a parameter is within its bound work exactly for wildcards? Given a class like this: class Foo<T extends Number> {} Experimenting with what the compiler accepts learns that: A ? extends wildcard using an unrelated interface type is allowed: Foo<? extends Runnable> is valid A ? extends wildcard using an unrelated class type is not allowed: Foo<? extends Thread> is invalid. That makes sense because no type can be a subtype of both Number and Thread In a ? super wildcard, the lower bound in the wildcard must be subtype of the bound

Consider the following code: public interface A { public A another(); } public interface B { public B another(); } public interface AB extends A,B { public AB another(); } This leads to a compile error on AB : types B and A are incompatible; both define another(), but with unrelated return types I've seen this SO question , and follow the incompatibility example in the the accepted answer - i.e. public interface C { public void doSomething(); } public interface D { public boolean doSomething(); } public interface CD extends C,D { } However, in that case the return types were genuinely

Please refer to the below code. When I run the code, I am able to change the value of a final non-static variable. But if I try to change the value of a final static variable then it throws java.lang.IllegalAccessException . My question is why doesn't it throw an exception in case of non-static final variable also or vice versa. Why the difference? import java.lang.reflect.Field; import java.util.Random; public class FinalReflection { final static int stmark = computeRandom(); final int inmark = computeRandom(); public static void main(String[] args) throws SecurityException,

Just when I thought I understood JLS15.12 as it applied to varargs, here's this example: package com.example.test.reflect; public class MethodResolutionTest2 { public int compute(Object obj1, Object obj2) { return 42; } public int compute(String s, Object... objects) { return 43; } public static void main(String[] args) { MethodResolutionTest2 mrt2 = new MethodResolutionTest2(); System.out.println(mrt2.compute("hi", mrt2)); System.out.println(mrt2.compute("hi", new Object[]{mrt2})); System.out.println(mrt2.compute("hi", new Object[]{mrt2, mrt2, mrt2})); } } which prints out 42 43 43 I