Strange Null pointer exception case: ternary conditional operator not working with string concatenation

Question

StringBuffer sb=null;

// Some more logic that conditionally assigns value to the StringBuffer

// Prints Value=null
System.out.println(\"Value=\"+sb);

// Throws Nu         


        

Answer 1

I think the issue is that the statement is being parsed like this:

System.out.println( ("Value="+sb) != null ? sb.toString() : "Null" );

The string concatenation operator (+) has a heigher precedence than the ternary operator.

Since "Value"+null is always not null, sb.toString() will always be called, even if sb is null, hence the NullPointerException.

If in doubt - parenthesize! Even if not in doubt! :)