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What does instance mean in java?

An instance refers to an object implementation based on a certain class. This process is called instantiation. Instance generation method: 1. Use the new keyword to generate. 2. Use the newInstance method of the Class class. 3. Use the newInstance method of the Constructor class.

Dec 04, 2019 pm 04:31 PM

java

How to get the first non-repeating character in a string in java

The method of "java" to obtain the first non-repeating character in a string is: first obtain the string data input by the user through the "Scanner" class, and then obtain the index and number of the last time a certain character appeared in the string. The index that appears in the string once can be determined by using the "if" statement.

Dec 04, 2019 pm 04:26 PM

java 获取字符串不重复字符第一个

java error: main class not found or unable to load solution

Java error: The main class cannot be found or cannot be loaded. Solution: Use "java package name + class name" to solve the problem. This error occurs because the java command by default searches in the directory specified in the CLASSPATH environment variable when searching for the address of the class file.

Dec 04, 2019 pm 04:06 PM

java 错误

Garbled characters appear when exporting queried data as a csv file in Java

The reason why garbled characters appear when the queried data is exported as a "csv" file in "java" is that the file exported in "csv" mode does not contain "BOM" information by default. The solution is to set the "BOM" identifier (byte stream starting with "EF", "BB", "BF") for the content to be output.

Dec 04, 2019 pm 03:46 PM

java 数据 csv 导出乱码

How to avoid reading garbled files in java

How to avoid reading garbled files in java: check the file encoding before reading the file in java, and then use the encoding of the file when java uses the InputStreamReader() method to read the file, so that garbled characters will not appear.

Dec 04, 2019 pm 03:46 PM

java

Java download file name garbled problem

Solution to the garbled file name of java downloaded file: 1. Use the URLEncoder.encode() method to set the encoding format of the downloaded file for IE or a browser based on IE. 2. For non-IE browsers, use the String(byte[],decode) method to specify the file encoding.

Dec 04, 2019 pm 03:23 PM

java

How to open exe file in java

The method of opening an "exe" file in "java" is: first use the "Runtime" class to obtain an instance of the current program, then create a process variable, then use the "exec" method to execute the file, and finally try to capture the file execution process through the exception mechanism possible exceptions.

Dec 04, 2019 pm 02:49 PM

java exe 文件

Java method to determine whether a time is today

How to determine whether a time is today in java: first specify the start and end of the day's time, and then use the java.time.LocalTime.isAfter() and java.time.LocalTime.isBefore() methods to determine whether the specified time is between the days of the day. .

Dec 04, 2019 pm 02:44 PM

java

Solution to java garbled code problem

Solution to java garbled code: 1. jsp page garbled code: add pageEncoding="UTF-8" statement to set the page encoding to solve the problem. 2. The garbled string transmitted from the background to the front end can be solved by using the setCharacterEncoding("UTF-8") statement to set the encoding during transmission.

Dec 04, 2019 pm 02:31 PM

java 乱码

How to package into jar package in java

The method of packaging "java" into a "jar" package is: first use "javac" to compile the "java" file to get the "class" file, then create a new file, and then put the compiled "class" file and the newly created file Enter the specified folder, and finally use the "jar" command to package it.

Dec 04, 2019 pm 02:24 PM

java 打包 jar包

How to open java binary file

In Java, you can use FilenputStream, a subclass of InputStream, to read binary files. The FileInputStream stream is called a file byte input stream, which refers to reading file data in the form of bytes.

Dec 04, 2019 pm 02:11 PM

java

Java determines whether a character is a number

How to determine whether a character is a number in java: 1. Use the isDigit() method to determine whether a character is a number. 2. First define the regular expression "[0-9]*", and then use the matches() method to match the regular expression to determine whether the character is a digit. 3. Use the ASCII code of the character to determine whether the character is numeric.

Dec 04, 2019 pm 01:54 PM

java

How to implement polymorphism in java

Java polymorphism means dynamic binding of methods during specific access. Java's implementation of dynamic binding of method calls mainly relies on the method table, which can be achieved through the class reference invocation (invokevitual) and interface reference invocation (invokeinterface) methods.

Dec 04, 2019 am 11:48 AM

java 多态

Introduction to the method of determining whether a variable is of type int in java

In Java, you can use the instanceof keyword to determine whether a variable is of type int. Strictly speaking, the instanceof keyword is a binary operator in Java, used to test whether an object is an instance of a class. You can determine whether a variable is of type int by judging whether it is an instance of type int.

Dec 04, 2019 am 11:23 AM

java