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A NullPointerException is an exception thrown by the Java Virtual Machine when you try to access a variable as if it were an object when it is contains null. For example, the following code would throw a NullPointerException:
String s;
if (s.charAt(0) == 'c') // this line throws NullPointerException
return "s[0] is 'c'";
What else can I help you with?
Can NullPointerException be used with ArithmaticException using throws keyword in java?
No. You cannot throw or catch Null pointer exceptions
How overcome problem of NullPointerException?
A NullPointerException is thrown when you attempt to access an object reference which is null. Example: String str = null; str.equals("x"); // <- NullPointerException To fix it, you must read the error message and find out what object is null. Determining how to ensure that this object is not set to null in the future must be made on a case-by-case basis.
What are the errors in this code?
the code is: function pppf($var1) { // Get PPPF Code Infomation $sql = "SELECT * FROM pppf_code"; $pppf_query = mysql_query($sql); while($pppf = mysql_fetch_assoc($pppf_query)) { $y = mysql_num_rows($pppf_query); if ($x<=$y) { $pppf_i = $pppf['input_text']; $pppf_o = $pppf['output_text']; $pppf_input = array($pppf_input.", '$pppf_i'"); $pppf_output = array($pppf_output.", '$pppf_o'"); } } echo $pppf_input['0']." | ".$pppf_output['0']."<br>"; $pppf_out = str_replace($pppf_input, $pppf_output, $var1); echo $pppf_out; }
Does exception always signal an error?
It depends on exactly how you define an error. If an exception is thrown, then it means something has gone wrong. Some Exceptions, such as a NullPointerException, will almost certainly signal an error in your code or data. Others, such as IOExceptions, can be caused by things outside your control, and would probably not be considered errors.
What are Class Constructor and Primitive data types?
class constructor is a function which has the same name as the class name and has no return type. primitive data types are the fundamental data types which are independent. eg:int,char,float etc..............
How do you overcome problem of NullPointerException?
By making sure that we do a null check everytime before using reference variables.
Can NullPointerException be used with ArithmaticException using throws keyword in java?
No. You cannot throw or catch Null pointer exceptions
What do you mean by NullPointer Exception?
NullPointerException - Is Thrown when attempting to access an object with a reference variable whose current value is null.
Throws statement in java?
throw new Throwable(); or throw new Error("Danger will Robinson!"); or throw new NullPointerException(); etc.
How overcome problem of NullPointerException?
A NullPointerException is thrown when you attempt to access an object reference which is null. Example: String str = null; str.equals("x"); // <- NullPointerException To fix it, you must read the error message and find out what object is null. Determining how to ensure that this object is not set to null in the future must be made on a case-by-case basis.
What are the errors in this code?
the code is: function pppf($var1) { // Get PPPF Code Infomation $sql = "SELECT * FROM pppf_code"; $pppf_query = mysql_query($sql); while($pppf = mysql_fetch_assoc($pppf_query)) { $y = mysql_num_rows($pppf_query); if ($x<=$y) { $pppf_i = $pppf['input_text']; $pppf_o = $pppf['output_text']; $pppf_input = array($pppf_input.", '$pppf_i'"); $pppf_output = array($pppf_output.", '$pppf_o'"); } } echo $pppf_input['0']." | ".$pppf_output['0']."<br>"; $pppf_out = str_replace($pppf_input, $pppf_output, $var1); echo $pppf_out; }
Does exception always signal an error?
It depends on exactly how you define an error. If an exception is thrown, then it means something has gone wrong. Some Exceptions, such as a NullPointerException, will almost certainly signal an error in your code or data. Others, such as IOExceptions, can be caused by things outside your control, and would probably not be considered errors.
What are the different types of exception?
Exceptions in programming can be categorized into several types, primarily into checked and unchecked exceptions. Checked exceptions are those that must be either caught or declared in the method signature, such as IOException in Java. Unchecked exceptions, like NullPointerException, do not require explicit handling and typically indicate programming errors. Additionally, there are system exceptions related to runtime issues and user-defined exceptions that developers create for specific application needs.
What is an example of a runtime error in java?
A common example of a runtime error in Java is the NullPointerException. This occurs when a program attempts to use an object reference that has not been initialized or is set to null. For instance, calling a method on a null object will trigger this error, leading to program termination unless properly handled through exception handling mechanisms. Runtime errors typically arise during the execution of the program, as opposed to compile-time errors, which are detected during the compilation process.
Difference between checked and unchecked exception?
Checked exceptions are exceptions which need to be handled explicitly. These are the ones which require a try-catchblock or a throws keyword.Unchecked exceptions are exceptions which have no obligation to be handled. A NullPointerException is one common example.
What is exception and list some of the common type of exception?
Exceptions are thrown when Java encounters an error. They are a fundamental part of the Java error handling system. In a nutshell, Java will throw an Exception when it encounters an error so that an exception handler can "handle" the error. For instance, if a calculator program is given the command "1/0", Java can throw an ArithmeticException which could be reported back to the user.Some common types are:ArithmeticException - thrown when arithmetic error has occurred, like dividing by 0IOException - thrown when an input or output error has occurred, like a file not foundArrayIndexOutOfBoundsException - thrown when a nonexistent element of an array is requested, like arr[-1]NullPointerException - thrown when some operation if performed on an object whose value is nll.
What are Class Constructor and Primitive data types?
class constructor is a function which has the same name as the class name and has no return type. primitive data types are the fundamental data types which are independent. eg:int,char,float etc..............
