publicclassDemo{publicstaticvoidmain(String[]args){String mystr=null;System.out.println(mystr.length());}} Output: Exception in thread "main" java.lang.NullPointerException: Cannot invoke "String.length()" because "mystr" is nullat com.example.myJavaProject.Demo.main(Demo.java:18) ...
In java (null) is valid but if we write (NULL, 0, Null), etc these word is invalid and there is no sense).Example:class NullCaseSensitive{ public static void main(String[] args) throws Exception{ /*We are assigning null in str1 and it will execute without any error*/ String str1...
Java Exception Hierarchy: In Java, all exceptions and errors inherit from the Throwable class, which is the root of the exception hierarchy. This hierarchy is divided into two main branches. Exception: This branch includes conditions that programs can handle, such as IOException, which occurs when...
In this context, explicitly assigning null to a reference does not directly influence the garbage collection process, as the key factor is the lack of live threads maintaining access to the object.ConclusionJava's garbage collection simplifies memory management and reduces the risk of memory-related...
3.java中的异常类分为三种类型:系统错误、异常和运行时异常。 系统错误是有JVM抛出的,用Error类表示。 异常用Exception类表示,包括ClassNotFoundException类、IoException类等等。 运行时异常用RuntimeException类表示,描述的是代码的错误。如ArithmeticException类、NullPointerException类、IndexOutOfBoundsException类、Illega...
【Java8】 Optional 详解 一、简介 Optional类是Java8为了解决null值判断问题,借鉴google guava类库的Optional类而引入的一个同名Optional类,使用Optional类可以避免显式的null值判断(null的防御性检查),避免null导致的NPE(NullPointerException)。 我们来看一段代码:...
What is chained exception explain with example? Chained Exception was added to Java in JDK 1.4. ... For example, considera situation in which a method throws an ArithmeticException because of an attempt to divide by zero but the actual cause of exception was an I/O error which caused the...
classMyClass{StringmyAttribute;}MyClassmyObject=null;System.out.println(myObject.myAttribute);#Output:#Exceptionin thread"main"java.lang.NullPointerException Java Copy In the above example, we try to accessmyAttributefrommyObject, which isnull. This results in a Null Pointer Exception. ...
Is NullPointerException checked or unchecked? NullPointerException is anunchecked exceptionand extends RuntimeException class. Hence there is no compulsion for the programmer to catch it. Is FileNotFoundException checked or unchecked? FileNotFoundException isa checked exception in Java. Anytime, we wa...
That is implementation specific, and you won't be able to see the representation ofnullin a pure Java program. (Butnullis represented as a zero machine address / pointer in most if not all Java implementations.) 意思是这个跟Java语言无关,是由Java实现自己去决定的,但大多数实现都是把它放在了...