Some notes on understanding the use of arrays in Java

1. Array elements are variables;

2. With square brackets [] After the existing data type, a new array type is generated;

Divided into two categories: 1) Basic data types, such as: int[],string[];

2) Reference data type, such as: person[] (Class);

The variables declared by the 3.main method are local variables, which are stored in the stack;

4. Array elements, as part of an array object, are always stored in heap memory, whether they are primitive data types or array elements of reference data types;

5. When accessing an instance property by referencing a variable or calling a non-static method, if the reference variable has not yet referenced a valid object (that is, unallocated memory space), the program throws a nullpointerexception run-time exception (runtime exception);

6.Cats is a custom class, cats as a cat[] array, is an array reference type; cats][0],cats][1] as an array element, is part of an array object;

Some notes on understanding the use of arrays in Java