The difference between int and Integer
The difference between int and Integer
1. Integer is a wrapper class of int, and int is a basic data type of java
2. Integer variables must be instantiated before they can be used, while int variables do not.
3. Integer is actually a reference to an object. When a new Integer is created, a pointer is actually generated pointing to this object. ; while int directly stores data values
4. The default value of Integer is null, and the default value of int is 0
Recommended learning: java tutorial
Extension:
Comparison between Integer and int
1. Since the Integer variable is actually a reference to an Integer object, the two are generated through new Integer variables are always unequal (because new generates two objects with different memory addresses).
Integer i = new Integer(100); Integer j = new Integer(100); System.out.print(i == j); //false
2. When comparing Integer variables with int variables, as long as the values of the two variables are equal, the result is true (because when the packaging class Integer is compared with the basic data type int, java will automatically unpack is int, and then the comparison actually becomes a comparison of two int variables)
Integer i = new Integer(100); int j = 100; System.out.print(i == j); //true
3. When the Integer variable generated by non-new is compared with the variable generated by new Integer(), the result is false. (Because the Integer variable generated by non-new points to an object in the Java constant pool, and the variable generated by new Integer() points to a newly created object in the heap, the two have different addresses in memory)
Integer i = new Integer(100); Integer j = 100; System.out.print(i == j); //false
4 . For two non-new generated Integer objects, when comparing, if the values of the two variables are between -128 and 127, the comparison result is true. If the values of the two variables are not in this range, the comparison result is false
Integer i = 100;Integer j = 100; System.out.print(i == j); //trueInteger i = 128; Integer j = 128; System.out.print(i == j); //false
For the reason for item 4:
When java compiles Integer i = 100;, it will be translated into Integer i = Integer.valueOf(100);, and the Integer type in the java API The definition of valueOf is as follows:
public static Integer valueOf(int i){ assert IntegerCache.high >= 127; if (i >= IntegerCache.low && i <= IntegerCache.high){ return IntegerCache.cache[i + (-IntegerCache.low)]; } return new Integer(i); }
java will cache numbers between -128 and 127. When Integer i = 127, 127 will be cached, and Integer j = 127 will be written next time. When, it will be fetched directly from the cache, and it will not be new.
For moreprogramming learning courses, you can pay attention to the PHP Chinese website!
The above is the detailed content of The difference between int and Integer. 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



In C language, the main difference between char and wchar_t is character encoding: char uses ASCII or extends ASCII, wchar_t uses Unicode; char takes up 1-2 bytes, wchar_t takes up 2-4 bytes; char is suitable for English text, wchar_t is suitable for multilingual text; char is widely supported, wchar_t depends on whether the compiler and operating system support Unicode; char is limited in character range, wchar_t has a larger character range, and special functions are used for arithmetic operations.

The difference between multithreading and asynchronous is that multithreading executes multiple threads at the same time, while asynchronously performs operations without blocking the current thread. Multithreading is used for compute-intensive tasks, while asynchronously is used for user interaction. The advantage of multi-threading is to improve computing performance, while the advantage of asynchronous is to not block UI threads. Choosing multithreading or asynchronous depends on the nature of the task: Computation-intensive tasks use multithreading, tasks that interact with external resources and need to keep UI responsiveness use asynchronous.

char and unsigned char are two data types that store character data. The main difference is the way to deal with negative and positive numbers: value range: char signed (-128 to 127), and unsigned char unsigned (0 to 255). Negative number processing: char can store negative numbers, unsigned char cannot. Bit mode: char The highest bit represents the symbol, unsigned char Unsigned bit. Arithmetic operations: char and unsigned char are signed and unsigned types, and their arithmetic operations are different. Compatibility: char and unsigned char

C language functions are the basis for code modularization and program building. They consist of declarations (function headers) and definitions (function bodies). C language uses values to pass parameters by default, but external variables can also be modified using address pass. Functions can have or have no return value, and the return value type must be consistent with the declaration. Function naming should be clear and easy to understand, using camel or underscore nomenclature. Follow the single responsibility principle and keep the function simplicity to improve maintainability and readability.

C language functions are reusable code blocks. They receive input, perform operations, and return results, which modularly improves reusability and reduces complexity. The internal mechanism of the function includes parameter passing, function execution, and return values. The entire process involves optimization such as function inline. A good function is written following the principle of single responsibility, small number of parameters, naming specifications, and error handling. Pointers combined with functions can achieve more powerful functions, such as modifying external variable values. Function pointers pass functions as parameters or store addresses, and are used to implement dynamic calls to functions. Understanding function features and techniques is the key to writing efficient, maintainable, and easy to understand C programs.

Multithreading is an important technology in computer programming and is used to improve program execution efficiency. In the C language, there are many ways to implement multithreading, including thread libraries, POSIX threads, and Windows API.

H5. The main difference between mini programs and APP is: technical architecture: H5 is based on web technology, and mini programs and APP are independent applications. Experience and functions: H5 is light and easy to use, with limited functions; mini programs are lightweight and have good interactiveness; APPs are powerful and have smooth experience. Compatibility: H5 is cross-platform compatible, applets and APPs are restricted by the platform. Development cost: H5 has low development cost, medium mini programs, and highest APP. Applicable scenarios: H5 is suitable for information display, applets are suitable for lightweight applications, and APPs are suitable for complex functions.

Export password-protected PDF in Photoshop: Open the image file. Click "File"> "Export"> "Export as PDF". Set the "Security" option and enter the same password twice. Click "Export" to generate a PDF file.
