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Summary of java basic knowledge

Basic knowledge of Java includes the history and characteristics of Java, Java development environment, Java's basic data types, variables and constants, operators and expressions, control statements, arrays and strings, etc. Friends who want to know more about the basic knowledge of Java, please read the relevant articles below this topic. Welcome to come to the PHP Chinese website to learn.

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java Basic data types byte variable final Bit shift operator ternary operator javaoperator puzzle regular expression replace string matching type of data java regular expression user input process control java control statement Statement usage

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Summary of java basic knowledge

What are the basic data types in java

The basic data types of Java are: 1. Boolean type; 2. Byte type; 3. Short integer type; 4. Integer type int; 5. Long integer type; 6. Single precision floating point type float; 7. , double precision floating point type double; 8. Character type char.

Aug 21, 2020 am 10:47 AM

java Basic data types

What are the similarities and differences between wrapper types and basic data types in Java?

This article is from the Java introductory tutorial. It introduces the similarities and differences between packaging types and basic data types in Java. It has certain reference value and I hope it can help everyone. Basic types do not need to be created through the new keyword, and wrapper classes require the new keyword.

Aug 06, 2020 pm 05:17 PM

java Basic data types

What are the basic data types in Java?

1. Integer type, the value range of byte, short, int, longbyte: -128 ~ 127 (-2 to the 7th power to 2 -1) The value range of short: -32768 ~ 32767 (-2 to the 15th power of 2 -1) The value range of int: -2147483648~2147483647 (-2 to the 31st power to the 31st power of 2 -1) The value range of long: -9223372036854774808~9223372036854774807 ( -2 to the 63rd power to 2 to the 63rd power -1) 2. Floating point type, float, doublefloat and double all represent

Apr 19, 2023 pm 04:13 PM

java

java basic data types

The basic data types of Java are: 1. byte, used to process byte-level data such as files and network transmissions; 2. short, which can be used to save memory space; 3. int, the most widely used integer type; 4. long, used to handle integer calculations that require larger values; 5. float, used for scientific calculations and scenarios that require high-precision calculations; 6. double, the most widely used floating point number type; 7. char, which can represent any character; 8. boolean, used for conditional judgment and Boolean operations.

Aug 02, 2023 pm 02:16 PM

java Basic data types

How many bytes do each of Java's basic data types occupy?

Each of Java's basic data types occupies the following bytes: 1. The integer type byte occupies 1 byte, and the short occupies 2 bytes; 2. The floating-point type float occupies 4 bytes, and the double occupies 8 bytes; 3. char The type occupies 2 bytes.

Sep 12, 2020 am 11:14 AM

java Basic data types byte

final variable in java

Final variables can only be explicitly initialized once. A reference variable declared as Final can never be reassigned to refer to a different object. However, the data within the object can be changed. Therefore, the state of the object can change, but the reference cannot. For variables, the final modifier is usually used with static to make the constant a class variable. Example publicclassTest{ finalintvalue=10; //Thefollowingareexamplesofdeclaringconstants: &a

Sep 24, 2023 pm 08:49 PM

java variable final

Java I/O Operations - Wrapper Classes and Primitive Class Variables

Java input/output (I/O) operations play a vital role in handling various types of data, allowing us to read and write from different sources such as files, network connections, and standard input/output streams. When handling input and output in Java, we come across situations where we need to handle primitive data and object type data. Java provides two options to facilitate this: wrapper classes or use raw class variables directly. This tutorial will introduce us to wrapper classes and primitive data types. Each of these methods has its advantages and considerations, which we will delve into to help you make informed decisions when operating Java I/O. Primitive data types Primitive data types, such as "int", "f

Sep 14, 2023 am 10:45 AM

Valid final variables in try-with-resources in Java 9?

Any variables used in the TrywithResource statement need to be declared in the Try statement until Java8 version. Starting with Java 9, this restriction has been removed and any final or effectively final variables are already blocked on the attempt. EffectivelyFinal means that the variable cannot be changed once it is initialized. Example importjava.io.BufferedReader;importjava.io.File;importjava.io.FileReader;importjava.io.IOException;publicclassEffectivelyFina

Sep 20, 2023 am 08:25 AM

How to use unsigned right shift in java

The usage of unsigned right shift in Java is to move a binary number to the right by the specified number of bits and fill it with zero bits on the left, regardless of the sign bit of the original number. The syntax of the unsigned right shift operator is "int result = value >>> num;", where value is the binary number to be moved, num is the number of digits to be moved, and result is the operation result.

Oct 12, 2023 am 11:32 AM

java Bit shift operator

Detailed introduction to java bit shift operator

Java bit shift operators are operators that operate on binary numbers. They shift the bits of a binary number to the left or right by a specified number of bits, and then fill in the zero bits or sign bits. There are three bit shift operators: left shift operator (<<), right shift operator (>>), and unsigned right shift operator (>>>).

Oct 12, 2023 am 11:19 AM

java Bit shift operator

How to calculate left shift operator in java

Calculation method: 1. Convert the binary number to be moved into binary format; 2. Move the binary number to the left by the specified number of digits, and fill in zero bits on the right side after the movement. For example, shift the binary number 1010 to the left by 2 bits to obtain 00101000; 3. Convert the shifted binary number to a decimal number, which is the calculation result of the left shift operator. For example, converting 00101000 to decimal gives 40.

Oct 12, 2023 am 11:22 AM

java Bit shift operator

Java ternary operator puzzle

What are operators in Java environment? Operators are some special characters or symbols or data designators in the Java environment that can perform certain operations. There are multiple operands (variables) that can participate in the operation here. After successful compilation, we get the desired output. There are many operators in the Java language, which are mainly used to manipulate the actual values of key variables present in the Java build code. For ternary operations, there is a condition, followed by a question mark (?), then an expression that executes the method if the condition is true, followed by a colon (:), and finally an expression that executes if the condition is false. Ternary statements should only be used when the resulting statement is too short to perform the procedure. Otherwise you should write the normal statement as an "if statement"

Sep 23, 2023 am 08:17 AM

ternary operator javaoperator puzzle

How to use java right shift operator

Java right shift operator usage: 1. Signed right shift, moves a binary number to the right by the specified number of digits, and fills the digits on the left according to the sign bit of the original number. If the original number is a positive number, it is on the left Fill zero bits, if the original number is a negative number, fill one 1 on the left; 2. Unsigned right shift, move a binary number to the right by the specified number of digits, and fill zero bits on the left, regardless of the original number sign bit.

Oct 12, 2023 am 11:30 AM

java Bit shift operator

Java development: How to use regular expressions for string matching and replacement

Java Development: How to Use Regular Expressions for String Matching and Replacement Regular expressions are a powerful tool that can be used to match, find, and replace specific content in strings. In Java development, regular expressions are often used to process various text operations. This article will introduce how to use regular expressions to match and replace strings in Java development, and provide specific code examples. Using the Pattern and Matcher classes The regular expression function in Java is mainly composed of Pattern and Matcher

Sep 21, 2023 pm 02:52 PM

regular expression replace string matching

Find user input data type using regular expression in Java

In Java programming, determining the type of information entered by the client can be a common task, especially when creating applications that require approval or processing of information. Regular expressions or regular expressions are an effective tool for identifying string designs and calculating categories of information. This article will examine a unique method of using standard expressions in Java to find the type of information entered by the client. Syntax The language constructs for regular expressions in Java are based on the java.util.regex package. It provides classes such as Design and Matcher to handle regular expression design and perform coordination operations. Syntax Description To use regular expressions in Java, we first need to create a regular expression pattern using the Design class. This pattern means we need

Sep 14, 2023 pm 10:33 PM

type of data java regular expression user input

How to use Java language flow control statements

The Java language is a high-level programming language, and its flow control statements are a very important part of programming. In Java, flow control statements can be used to control the execution sequence of the program, determine conditions, and execute a certain code block in a loop to achieve program flexibility and controllability. There are three main types of flow control statements in Java language: sequence structure, selection structure and loop structure. Next, we will introduce the use of these three flow control statements in detail. 1. Sequential structure Sequential structure means that the program is executed sequentially in the order in which the code is written.

Jun 09, 2023 pm 08:36 PM

process control java control statement Statement usage