Why do java if statement fail when it ends in semicolon [duplicate]

Answer 1

Your code is equivalent to:

if(name != null && value != null) {
   // empty code block
}

System.out.println("Values not null");

Answer 2

if(name != null && value != null);
{
    System.out.println("Values not null");
}

is equivalent to:

if(name != null && value != null){}

{
    System.out.println("Values not null");
}

Answer 3

if(name != null && value != null);

Here your if statement got finished due to semi-colon...

So, it is just like an empty if block: -

if(name != null && value != null) {}

So your next code becomes an Initializer block: -

{
    System.out.println("Values not null");
}

Since it is an initializer block.. It will be executed always no matter what your if condition evaluated to..

Answer 4

One bare ; is a whole empty statement. After the if there has to be exactly one statement that will be executed when if is true. The one statement that is executed in your case is the empty statement. You can combine more statements to one with {statement; statement;...}

Answer 5

The semi-colon ends the statement, and thus detaches the if from the following block.

Note that blocks can be arbitrary.

{
System.out.println("This is some code");
}

if(true); This is valid, and it does nothing. The language allowing this is pretty stupid, although IDEs should catch these issue with warnings and the like.

Answer 6

Understand that conditional statements needn't always follow with opening and closing braces. Most languages will allow you to simply emit the braces if you only want to execute a single statement when the terms of the condition are met.

Meaning that the following is completely valid, for instance:

if (var1 == true && var2 == true) var3 = 'both true';
{
    //block here, this is always executed regardless of the statements outcome
}

Essentially, your code does exactly this. Except your single statement is determined to be ; (yes, this is considered a statement).

What you wrote is the same as:

if(name != null && value != null) {
    // do nothing
}

System.out.println("Values not null");