What is initialization in java

What is initialization in java

Initialization is to give a variable an initial value.

For example:

Declare a variable: String php = "www.php.cn"; int score = 100; where www.php.cn and 100 are the initialization values. The final value is not necessarily www.php.cn or 0.

If you overwrite the value of php as follows:

php = "wap.php.cn"; score = 101; Then the final value of the php variable is wap.php.cn, score variable That’s 101. The purpose of initialization is to make the variable have a value and prevent exceptions when using it.

Extended information:

Function

1. When encountering the four bytecode instructions new, getstatic, putstatic, or invokestatic, if If the class has not been initialized, its initialization needs to be triggered first. The most common Java code scenario for generating these four instructions is:

When using the new keyword to instantiate an object, read or set a static field of a class (modified by final, and the result has been put in the mutation period (except for static fields entered into the constant pool), and when calling static methods of a class.

2. When using the method of the java.lang.reflect package to make a reflective call to a class, if the class has not been initialized, you need to initialize it first.

3. When initializing a class, if you find that its parent class has not been initialized, you need to initialize its parent class first.

4. When the virtual machine starts, the user needs to specify a main class to be executed (the class containing the main() method), and the virtual machine will first initialize the main class.

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