Java
javaTutorial
Detailed comparison of basic type variables and reference type variables in Java
Detailed comparison of basic type variables and reference type variables in Java
Basic type:
It goes without saying that the basic type is a number, a character or a Boolean value.
Reference type:
is an object type, what is the value? Its value is a reference to the memory space, which is the address. The memory pointed to holds a value or a set of values represented by the variable.
Example:
int a;
a=250; //When declaring variable a, the system allocates space to a.
The reference type is not. Only the reference space is allocated to the variable, and the data space is not allocated, because no one knows what the data is, integer, character? Let's look at an error example:
MyDate today;
today.day = 4; //An error occurred because the data space of the today object is not allocated.
Then how do we assign a value to it? After declaration, a reference type variable must open up data space through instantiation before the object pointed to by the variable can be accessed. For example:
MyDate today; //Allocate the variable to a space to save the reference
today = new MyDate(); //This sentence is a 2-step process, first execute new MyDate( ), open up a data space for the today variable, and then perform the assignment operation
//Assignment of reference variables
MyDate a, b; #a = new MyDate(); //Open up the data space of the MyDate object, and assign the first address of the space to a
b = a; //Write the address in the storage space of a to the storage of b In the space
As shown below
Reference type:
Except when a function passes a value, it is "pass by reference". Any time "=" is used to assign a value to an object variable, it is "pass by reference".
Value transfer:The transfer of basic types belongs to value transfer, just like C language, when Java’s basic data types (such as
int, char, double, etc.) are passed to the function body as entry parameters, the passed parameters become local variables inside the function body. This local variable is a copy of the input parameter. All functions
The internal operations of the number body are all operations on this copy. After the function execution is completed, this local variable has completed its mission, and it will not affect the variables used as input parameters. Parameter passing in this way is called "value
Pass"./*define a class*/class MyDate{
String Year;
String Month;
String Day;
String Date; public MyDate(){
Year = "1900";
Month ="01";
Day = "01";
Date = Year + "." + Month + "."+ Day;
} public String toString(){ return Date;
}
}public class ObjRef{
MyDate mydate1 = new MyDate();
MyDate mydate2 = mydate1;// = 使 mydate1和 mydate2将指向同一内存空间 //MyDate mydate2 = new MyDate();//从新new一个对象，则mydate1和mydate2是指向不同的内存空间的： //引用空/间和数据空间都不一样
public void changeObj(MyDate inObj){
inObj.Date = "2007.09.26";
}
public static void main(String[] args) {
ObjRef oRef = new ObjRef();
System.out.println("Before call changeObj() method: " + oRef.mydate1);
oRef.changeObj(oRef.mydate1);
System.out.println("After call changeObj() method: " + oRef.mydate1);
System.out.println("After call changeObj() method: " + oRef.mydate2);//验证“= mydate1和 mydate2将指向同一内存空间“这一结论
}
}
The above is the detailed content of Detailed comparison of basic type variables and reference type variables in Java. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
Java Spring Interview Questions
Aug 30, 2024 pm 04:29 PM
In this article, we have kept the most asked Java Spring Interview Questions with their detailed answers. So that you can crack the interview.
Break or return from Java 8 stream forEach?
Feb 07, 2025 pm 12:09 PM
Java 8 introduces the Stream API, providing a powerful and expressive way to process data collections. However, a common question when using Stream is: How to break or return from a forEach operation? Traditional loops allow for early interruption or return, but Stream's forEach method does not directly support this method. This article will explain the reasons and explore alternative methods for implementing premature termination in Stream processing systems. Further reading: Java Stream API improvements Understand Stream forEach The forEach method is a terminal operation that performs one operation on each element in the Stream. Its design intention is
TimeStamp to Date in Java
Aug 30, 2024 pm 04:28 PM
Guide to TimeStamp to Date in Java. Here we also discuss the introduction and how to convert timestamp to date in java along with examples.
PHP: A Key Language for Web Development
Apr 13, 2025 am 12:08 AM
PHP is a scripting language widely used on the server side, especially suitable for web development. 1.PHP can embed HTML, process HTTP requests and responses, and supports a variety of databases. 2.PHP is used to generate dynamic web content, process form data, access databases, etc., with strong community support and open source resources. 3. PHP is an interpreted language, and the execution process includes lexical analysis, grammatical analysis, compilation and execution. 4.PHP can be combined with MySQL for advanced applications such as user registration systems. 5. When debugging PHP, you can use functions such as error_reporting() and var_dump(). 6. Optimize PHP code to use caching mechanisms, optimize database queries and use built-in functions. 7
Java Program to Find the Volume of Capsule
Feb 07, 2025 am 11:37 AM
Capsules are three-dimensional geometric figures, composed of a cylinder and a hemisphere at both ends. The volume of the capsule can be calculated by adding the volume of the cylinder and the volume of the hemisphere at both ends. This tutorial will discuss how to calculate the volume of a given capsule in Java using different methods. Capsule volume formula The formula for capsule volume is as follows: Capsule volume = Cylindrical volume Volume Two hemisphere volume in, r: The radius of the hemisphere. h: The height of the cylinder (excluding the hemisphere). Example 1 enter Radius = 5 units Height = 10 units Output Volume = 1570.8 cubic units explain Calculate volume using formula: Volume = π × r2 × h (4
PHP vs. Python: Understanding the Differences
Apr 11, 2025 am 12:15 AM
PHP and Python each have their own advantages, and the choice should be based on project requirements. 1.PHP is suitable for web development, with simple syntax and high execution efficiency. 2. Python is suitable for data science and machine learning, with concise syntax and rich libraries.
Create the Future: Java Programming for Absolute Beginners
Oct 13, 2024 pm 01:32 PM
Java is a popular programming language that can be learned by both beginners and experienced developers. This tutorial starts with basic concepts and progresses through advanced topics. After installing the Java Development Kit, you can practice programming by creating a simple "Hello, World!" program. After you understand the code, use the command prompt to compile and run the program, and "Hello, World!" will be output on the console. Learning Java starts your programming journey, and as your mastery deepens, you can create more complex applications.
How to Run Your First Spring Boot Application in Spring Tool Suite?
Feb 07, 2025 pm 12:11 PM
Spring Boot simplifies the creation of robust, scalable, and production-ready Java applications, revolutionizing Java development. Its "convention over configuration" approach, inherent to the Spring ecosystem, minimizes manual setup, allo
