Compile Time Error Example
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when you include disallowed characters in your code (e.g. int #people = 10;). Syntactical: These occur when your code is "out of order" (e.g. for (int i=0; i++; i<10)). Semantic: These occur when the meaning of your code is unclear (e.g. two compile time error definition variables with the same name). Note that the exact wording of these errors may vary, depending compile time error mooshak on which development environment you are using. Errors described on this page (click to jump to that error): Cannot return a value from run time error 1004 a method of type void 'Class' or 'interface' expected Class should be delcared abstract; it does not define... Else without if Expected: ;, {, }, (, or ) Identifier expected / Illegal character Incompatible types / Inconvertible types (cannot http://www.theserverside.com/tutorial/The-most-common-compile-time-errors-in-Java cast) Method does not return a value / Missing return statement Method not found Not a statement Return type required Unreachable statement Variable already defined Variable not declared Cannot return a value from a method of type void When a method is declared as having a return type of void, it cannot contain any return statements which return a value (it can, however, contain a return statement by itself, which will simply end the execution of https://www.student.cs.uwaterloo.ca/~cs133/Resources/Java/Debugging/compile.shtml the method). This problem is usually caused by accidentally making a method be of type void when it shouldn't be or by accidentally including a return statement where there shouldn't be one. Example 1: Incorrect Code Example 1: Fixed Code This method has a return type of void and so it may not return any values. We change the return type of this method in order to fix the problem. 01 public void getName() 02 { return this.name; 03 } 01 public String getName() 02 { return this.name; 03 } 'Class' or 'interface' expected This error will most likely be caused when you omit the keyword class or interface, as seen in the example below. Example 1: Incorrect Code Example 1: Fixed Code Here, we do not have either keyword present. We add in class or interface, depending on our intentions within the program. 01 public Test 02 { 03 public void someMethod() 04 { System.out.println("Hello, world!"); 05 } 06 } 01 public class Test 02 { 03 public void someMethod() 04 { System.out.println("Hello, world!"); 05 } 06 } -- OR -- 01 public interface Test 02 { 03 public void someMethod(); 04 } Class should be delcared abstract; it does not define... This error arises when implementing an interface. Recall that when you say implements SomeInterface for a certain class, you guarantee that you have written all of the me
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and http://stackoverflow.com/questions/846103/runtime-vs-compile-time policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users http://www.xyzws.com/javafaq/what-is-the-difference-between-compile-time-error-and-run-time-error/32 Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a time error minute: Sign up Runtime vs Compile time up vote 179 down vote favorite 171 Can anyone please give me a good understanding of whats the difference between run-time and compile-time? compiler-construction runtime compile-time share|improve this question edited Oct 31 '09 at 13:35 e-satis 250k82236286 asked May 10 '09 at 21:06 devforall 1,807112641 add a comment| 19 Answers 19 active oldest votes compile time error up vote 253 down vote accepted The difference between compile time and run time is an example of what pointy-headed theorists call the phase distinction. It is one of the hardest concepts to learn, especially for people without much background in programming languages. To approach this problem, I find it helpful to ask What invariants does the program satisfy? What can go wrong in this phase? If the phase succeeds, what are the postconditions (what do we know)? What are the inputs and outputs, if any? Compile time The program need not satisfy any invariants. In fact, it needn't be a well-formed program at all. You could feed this HTML to the compiler and watch it barf... What can go wrong at compile time: Syntax errors Typechecking errors (Rarely) compiler crashes If the compiler succeeds, what do we know? The program was well formed---a meaningful program in whatever language. It's possible to start running the program. (The program might fail immediately, but at least we can try.) What are the inputs and outputs? Input was the program being compiled, plus any header files,
error? At compile time, when the code does not comply with the Java syntactic and semantics rules as described in Java Language Specification (JLS), compile-time errors will occurs. The goal of the compiler is to ensure the code is compliant with these rules. Any rule-violations detected at this stage are reported as compilation errors. The best way to get to know those rules is to go through all the sections in the JLS containing the key words "compile-time error". In general, these rules include syntax checking: declarations, expressions, lexical parsing, file-naming conventions etc; exception handling: for checked exceptions; accessibility, type-compatibility, name resolution: checking to see all named entities - variables, classes, method calls etc. are reachable through at least one of the declared path; etc. The following are some common compile time errors: a class tries to extend more than one class overloading or overriding is not implemented correctly attempt to refer to a variable that is not in the scope of the current block an inner class has the same name as one of one of its enclosing classes a class contains one or more abstract methods and the class itself is not declared "abstract" a class tries to reference a private member of another class trying to create an instance of an abstract class trying to change the value of an already initialized constant (final member) declare two (class or instance) members with the same name Here is a list of conditions that may cause compile-time errors. When the code compiles without any error, there is still chance that the code will fail at run time. The errors only occurs at run time are call run time errors. Run time errors are those that passed compiler's checking, but fails when the code gets executed. There are a lot of causes may result in runtime errors, such as incompatible type-casting, referencing an invalid index in an array, using an null-object, resource problems like unavailable file-handles, out of memory situations, thread dead-locks, infinite loops(not detected!), etc. The following are some common runtime errors: trying to invoke a method on an uninitialized variable (NullPointerException) ran out memory (memory leaks...) (OutOfMe