Exception that the method cannot be found in Java - java.lang.NoSuchMethodException

In Java programming, a common exception is java.lang.NoSuchMethodException, which means that the definition of the method cannot be found in the given class. This is usually due to some common mistakes or misunderstandings.

First of all, the most common mistakes are spelling mistakes. In Java, method names are case-sensitive, so a misspelling can cause a method not found exception. For example, if your method name is "calculateTotal", but you write "CalculateTotal" in the code, Java will throw a NoSuchMethodException exception.

Secondly, the parameter type and number may also cause exceptions. In Java, method overloading allows multiple methods to be defined in the same class with the same name but different types or number of parameters. If you provide the wrong type or number of parameters when calling a method, Java will not be able to find the correct method. For example, given a method named "addNumbers", if you call it providing a string and an integer, and it actually requires two integers as parameters, a NoSuchMethodException will be thrown.

Another situation is that this method may not be defined in your code. If you try to call a method that does not exist according to the method name, Java will throw a NoSuchMethodException exception. This may be a method you use in another project, but this project is not referenced in your current project.

Finally, access modifiers may also cause exceptions. If your method is private, it can only be accessed from this class. If you access the method from other classes or packages, a NoSuchMethodException will be thrown.

To avoid this exception, you need to ensure that you use the correct name, parameter type and number when calling the method. If you encounter a NoSuchMethodException, you should double-check your code for errors and make sure you are spelling and calling methods correctly in your code.

In addition, you can also use the Java reflection mechanism to dynamically create method objects and call methods, which will allow you to detect method calling errors at compile time, thereby avoiding NoSuchMethodException exceptions.

In short, NoSuchMethodException is one of the common exceptions in Java. It is usually caused by spelling errors, wrong parameter types and numbers, undefined methods or wrong access modifiers. Writing clean and robust code and taking care to prevent these errors can effectively avoid this problem.

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