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What are the methods in Java to determine whether a string contains a specific string?

The methods in "java" to determine whether a string contains a specific string are: method 1, "startsWith" method, which is used to detect whether the string starts with the specified prefix; method 2, "contains" method, if and only Returns "true" when the string contains the specified sequence of "char" values.

Nov 30, 2019 am 10:55 AM

java judgment Include string

What does == symbol mean in java

"==" in Java is a relational operator, used to check whether the values ??of two operands are equal. If equal then the condition is true. For basic data types, == indicates whether the values ??are equal. For object data types, == indicates whether the address values ??are equal.

Nov 30, 2019 am 10:47 AM

java

Java method to determine whether it is an IP

Java can use matcher to match the regular expression "([1-9]|[1-9]\\d|1\\d{2}|2[0-4]\\d|25[0-5]) (\\.(\\d|[1-9]\\d|1\\d{2}|2[0-4]\\d|25[0-5])){3}" to judge .

Nov 30, 2019 am 10:37 AM

java

How to determine whether key exists in map collection in java

The method in "java" to determine whether "key" exists in the "map" collection is: first instantiate a "map" object, then add several elements to the collection for determination, and then use the "containsKey" provided by "java api" Method to judge or loop through, just compare one by one.

Nov 30, 2019 am 10:33 AM

java key judgment exist

Solution to string garbled characters in java

Java can transcode strings to solve string garbled characters. Use String(str.getBytes(charsetName), "utf-8") to change the string encoding format. charsetName is the original character encoding, and "utf-8" converts str to utf-8 encoding.

Nov 30, 2019 am 10:21 AM

java

Java method to determine whether it is json

Java can determine whether the data is in json format through exceptions. Use the JSONObject.parseObject (String str) method in try..catch to operate on json format data. If it is not json format data, false will be returned.

Nov 30, 2019 am 10:09 AM

java

Java uses if statement to determine whether a string is empty or null

The way "java" uses the "if" statement to determine whether a string is empty or "null" is: first distinguish the empty string and the "null" string, then determine whether it is the empty string by the length of the string, and then use "! The =" operator can determine whether the string is "null".

Nov 30, 2019 am 09:55 AM

if java null string null

Java determines whether a string is a number

How to determine whether a string is a number in Java: 1. Loop through the string, and then use the isDigit() function to determine whether a single character is a number. 2. Use the regular expression "^[-\\+]?[\\d]*$" to judge. 3. Judge by throwing exceptions.

Nov 30, 2019 am 09:53 AM

java

Java calculates the day of the week a date is

How to calculate the day of the week for a specified date in java: 1. Use the Calendar class to get the day of the week based on the date. This method returns a number from 1 to 7, representing the number of weeks from Sunday to Saturday. 2. Use the SimpleDateFormat class to get the day of the week for the specified date. Use the parameter EEEE to get the day of the week.

Nov 30, 2019 am 09:43 AM

java

Java implements a method to determine whether a file file exists

The method for "java" to determine whether the "file" file exists is: To determine whether the file exists, you can use the "file.exists" method of the "File" class. First, you need to import the "File" class, and then save the file path that needs to be determined to In the object, the final judgment can be made by calling the "exists" method.

Nov 30, 2019 am 09:40 AM

file java exist accomplish method

Solution to garbled characters in java reading txt files

When Java reads a txt file, you need to set the reading encoding. The encoding format of txt documents is written in the file header. In the program, the encoding format of the file needs to be parsed first. After obtaining the encoding format, reading the file in this format will not produce garbled characters.

Nov 30, 2019 am 09:32 AM

java

How to open specified exe file in java

The method for "java" to open a specified "exe" file is: first instantiate it through the static method of the "Runtime" class, then save the file to be run into a variable, then call the native program through exception handling, and finally Just print the exception information.

Nov 30, 2019 am 09:22 AM

exe java document

4 examples of ways to copy files in java

When we are doing Java programming, we often operate on files. This article introduces four methods of copying files in Java, which are copying using FileStreams, copying using FileChannel, copying using Commons IO, and copying using the Files class of Java7.

Nov 29, 2019 pm 05:38 PM

java

Java implements bubble sort algorithm

This article introduces the implementation of bubble sort from the java introductory program column. I hope it can help you. Bubble sort is an algorithm that compares adjacent elements and swaps their positions if they are in the wrong position. Sorting can be done in ascending or descending order.

Nov 29, 2019 pm 05:26 PM

java Bubble Sort algorithm