I accidentally wrote a java statement with two semicolons at the end. The java compiler does not show any error and it runs.
Code:
System.out.println("Length after delete the text is "+name.length());;
For learning purposes I tried adding different characters after the semicolon, and the java compiler has shown the compile time error as Syntax error on token ")", delete this token.
This statement:
System.out.println("Length after delete the text is "+name.length());)
Why does java treat the semicolon and other characters as different?
Because a double semicolon is not treated as a double semicolon but as a semicolon plus an empty statement. And an empty statement, which does nothing, is not an error.
As told by other answers, usually the second semicolon is interpreted as an empty statement, which is permissible where ever a statement is permissible.
Actually, there are cases where a double semicolon does produce an error:
public int method() {
return 1;;
}
When the compiler determines that a location is not reachable (and this is defined exactly in the JLS, but includes the locations directly after a return, break, continue and throw), no statement is allowed there, not even an empty one.
According to the Java language standard, the second semicolon is an empty statement.
An empty statement does nothing.
EmptyStatement:
;
Execution of an empty statement always completes normally.
; by itself is an empty operator, so you effectively have two operators in the original case.
The semicolon ends the sentence.
System.out.println("Length after delete the text is "+name.length());;
The second semicolon means the sentence is empty.
System.out.println("Length after delete the text is "+name.length());)
Is wrong because you're trying to finish an uncompleted sentence.
Because it is not error? Why you are asking about java? This is in most languages with similar syntax...
来源：https://stackoverflow.com/questions/9546455/why-does-java-not-show-an-error-for-double-semicolon-at-the-end-of-a-statement