Analysis of five data types in java

I don’t know if you know about Java’s simple data types. Here is a detailed explanation and analysis of Java’s five types of simple data types that represent numbers and characters.

1. Initialization of simple data types

In the Java language, simple data types are automatically initialized to default values ​​when declared as member variables of a class, unless explicitly declared. Simple data types are not automatically initialized when declaring local variables for a method and will cause the compiler to throw an error message similar to "Variable x may not have been initialized." Table B defines Java simple The default value of the data type.

2. Encapsulation classes

1ava also provides built-in encapsulation classes such as Byte, Short, Boolean, Character, Integer, Double, Float and Long. These wrapper classes provide very intuitive utility methods. For example, the Byte, Float, Integer, Long and Double classes all have the doubleValue() method, through which the value stored in the instance of the class can be converted to the Double type. In addition, all encapsulated classes provide a static valueOf(String s) method to convert a given String.

3. Data type

The data type is an abstract expression of the memory location. Programmers can take advantage of many data types: some are defined by the programming language, some are defined by external libraries, and some are defined by the programmer. Many programming languages ​​rely on specific computer types and specific compiled implementations of data type attributes, such as the size of word and integer data types. Java's virtual machine, on the other hand, is responsible for defining all aspects of its built-in data types. This means that no matter how low-level the operating system the Java Virtual Machine (JVM) is running on, the properties of the data type are exactly the same.

4. Default initial values ​​of Java simple data types

The code in Listing B shows that all Java simple data types are used as member variables of the Initialization class. This example also shows that an int variable is declared locally in the constructor of the Initialization class. Without modifying the above code, the compiler will throw an error when compiling the above code.

Once the line of code causing the problem (the code that refers to an uninitialized variable that causes the error) is deleted or commented out.

Summary: Java defines a full set of simple data types. In addition, Java eliminates the hardware and compiler dependencies found in other programming languages, allowing programmers to shift their attention to other problems. In the next article, we will continue to discuss some commonly used Java-defined complex data types and learn how to use them to solve typical programming problems.

5. Java’s simple data types

All numeric variables in Java are signed, and Java does not allow arbitrary conversion between data types. Type conversion is only possible between numeric variables. For example, boolean cannot be converted to other data types, and other data types cannot be converted to boolean. Because Java's simple data types are accurately defined, and direct memory access is not allowed, the sizeof operation is canceled in the Java language symbol. Java's simple data types are not objects. In order to take an object-oriented approach to Java's simple data types, you need to first encapsulate them with classes.

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