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Why can't java be installed? How to solve?

The reason is: the "JDK" environment does not correspond to the operating system or the installation directory is wrong. The solution is: first make sure that the downloaded "JDK" environment corresponds to your own operating system, and then when installing the "JDK" environment, make sure that the installation path of "JRE" is not under the file path of "JDK".

Dec 31, 2019 am 11:11 AM

java

Can java delete list elements?

Java can delete list elements. Methods: 1. Use the remove() method of Iterator; 2. Use the remove() method of List, paying attention to the position of list.size(); 3. Use CopyOnWriteArrayList.

Dec 31, 2019 am 10:54 AM

java list

How to get the first few digits of a string in java

How to get the first digits of a string in java: 1. Use the subString() method to intercept the string. subString provides different interception methods through different parameters, such as using substring(0,4) to intercept the first 4 digits. 2. Intercept through the methods provided by StringUtils.

Dec 31, 2019 am 10:46 AM

java 字符串

What types of streams are there in java?

Types of streams in Java: According to the direction of the stream: input stream and output stream. According to the implementation functions, there are: node flow and processing flow. According to the unit of data processing, there are: byte stream and character stream.

Dec 30, 2019 pm 05:41 PM

java 流

How to compare strings in java without case sensitivity

In Java, you can use the equalsIgnoreCase() method to implement case-insensitive comparison of strings. The equalsIgnoreCase() method is used to compare a string with a specified object, regardless of case. If the given object is equal to the string, it returns true. Otherwise return false.

Dec 30, 2019 pm 04:08 PM

java 字符串

How to solve the problem of garbled characters when reading csv files in Java

Solution to garbled characters in java when reading CSV files: Use the InputStreamReader class in the BufferedReader class to specify the encoding format for reading CSV files. The InputStreamReader class uses the specified character set to read bytes and decode them into characters.

Dec 30, 2019 pm 03:53 PM

java 乱码

How to determine whether ip is legal in java

In Java, you can first define a regular expression that matches the correct IP address, and then use the matches(regex) method to detect whether the given IP address matches the given regular expression to determine whether the IP is legal.

Dec 30, 2019 pm 03:27 PM

java ip

The difference between interface and inheritance in java

The difference between java interface and inheritance: 1. They are decorated with different modifiers. 2. Multiple inheritance is not supported in JAVA, but it can be implemented using interfaces. 3. Inheritance can only inherit one class, but implements can implement multiple interfaces.

Dec 30, 2019 pm 03:08 PM

java 接口继承

Java determines whether a thread is running

In Java, you can use Thread.isAlive() to determine whether a thread is running. The Thread.IsAlive attribute indicates whether the thread is currently available. If the thread has been started and there are no exceptions currently, it is true, otherwise it is false.

Dec 30, 2019 pm 02:15 PM

java 线程

How to solve garbled characters when writing files in Java

Java writing file solution: You can use OutputStreamWriter write=new OutputStreamWriter(new FileOutputStream(f), "UTF-8"); to specify the character set used when writing files.

Dec 30, 2019 pm 01:57 PM

java 乱码

How to output java string

Strings in Java can be output using System.out.println(). System is a class, inherited from the root class Object, out is an object instantiated by the PrintStream class, and println() is a member method of the PrintStream class.

Dec 30, 2019 pm 01:44 PM

java 输出

Java determines whether a string is empty

How to determine whether a string is empty in Java: 1. Use "str!=null" to determine. Null means that the string does not point to anything. 2. Use "".equals(str) to judge. 3. Use the "str.length()!=0" method to determine.

Dec 30, 2019 am 11:35 AM

java 字符串

Solution to garbled request in java

In Java, POST transmits garbled parameters through the request body, which can be solved by setting the encoding method of the response character stream to UTF-8. If the get mode is garbled, you can first set the request data to be encoded in ISO8859-1 mode, and then decrypt it in UTF-8 mode.

Dec 30, 2019 am 09:43 AM

java request 乱码

The problem of json transmission data garbled in java

Solution to the problem of json transmission data garbled in Java: 1. First encode the parameters with ISO-8859-1, and then decode them with utf-8. 2. If it is a general request, just configure the Chinese filter in web.xml.

Dec 30, 2019 am 09:24 AM

java json 乱码