Java Programming - Assertions - Discussion
public class Test
{
public void foo()
{
assert false; /* Line 5 */
assert false; /* Line 6 */
}
public void bar()
{
while(true)
{
assert false; /* Line 12 */
}
assert false; /* Line 14 */
}
}
Option D is correct. Compilation fails because of an unreachable statement at line 14. It is a compile-time error if a statement cannot be executed because it is unreachable. The question is now, why is line 20 unreachable? If it is because of the assert then surely line 6 would also be unreachable. The answer must be something other than assert.
Examine the following:
A while statement can complete normally if and only if at least one of the following is true:
- The while statement is reachable and the condition expression is not a constant expression with value true.
-There is a reachable break statement that exits the while statement.
The while statement at line 11 is infinite and there is no break statement therefore line 14 is unreachable. You can test this with the following code:
public class Test80
{
public void foo()
{
assert false;
assert false;
}
public void bar()
{
while(true)
{
assert false;
break;
}
assert false;
}
}
Compile Time Error is when the error is encountered at compilation, i.e before the program is actually executed. This error includes syntactical errors, type conversion error. Whereas run time error occurs when the program is getting executed, this can be due to any unexpected error like divide by 0 or when array index is accessed is not in range of the size of the array.
public class Test80
{
public void foo()
{
assert false;
assert false;
}
public void bar()
{
while(true)
{
assert false;
break;
}
assert false;
}
public static void main(String[] args){}
}
Thus the code is successfully compiled.
Before jdk 1.4 it has been treated as an identifier and onwards from 1.4 it has been first introduced as a keyword.
assert can be write in two ways:
Really simple:
assert(y>x) or assert true or assert false.
Which must result in boolean value.
Simple:
assert(y>x):"y is greater than x".
In first exp is same but second exp can be anything that results in a value.
How to identify whether it is a compilation error or run time error. Explain me in easy way. Now only I started to learn java.