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

Let's bracket the expression the way that the compiler effectively would, in the broken vase:

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

Now "Value" + sb will never be null even if sb is null... so when sb is null, it's calling toString() and going bang.