Look at the following infinite while loop in Java. It causes a compile-time error for the statement below it.
while(true) {
System.out.println("inside while");
}
System.out.println("while terminated"); //Unreachable statement - compiler-error.
The following same infinite while loop, however works fine and doesn't issue any errors in which I just replaced the condition with a boolean variable.
boolean b=true;
while(b) {
System.out.println("inside while");
}
System.out.println("while terminated"); //No error here.
In the second case also, the statement after the loop is obviously unreachable because the boolean variable b is true still the compiler doesn't complain at all. Why?
Edit : The following version of while gets stuck into an infinite loop as obvious but issues no compiler errors for the statement below it even though the if condition within the loop is always false and consequently, the loop can never return and can be determined by the compiler at the compile-time itself.
while(true) {
if(false) {
break;
}
System.out.println("inside while");
}
System.out.println("while terminated"); //No error here.
while(true) {
if(false) { //if true then also
return; //Replacing return with break fixes the following error.
}
System.out.println("inside while");
}
System.out.println("while terminated"); //Compiler-error - unreachable statement.
while(true) {
if(true) {
System.out.println("inside if");
return;
}
System.out.println("inside while"); //No error here.
}
System.out.println("while terminated"); //Compiler-error - unreachable statement.
Edit : Same thing with if and while.
if(false) {
System.out.println("inside if"); //No error here.
}
while(false) {
System.out.println("inside while");
// Compiler's complain - unreachable statement.
}
while(true) {
if(true) {
System.out.println("inside if");
break;
}
System.out.println("inside while"); //No error here.
}
The following version of while also gets stuck into an infinite loop.
while(true) {
try {
System.out.println("inside while");
return; //Replacing return with break makes no difference here.
} finally {
continue;
}
}
This is because the finally block is always executed even though the return statement encounters before it within the try block itself.