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- How to determine whether an object is empty in java
- Methods to determine whether an object is empty in java: 1. Use the StringUtils.isEmpty(CharSequence cs); method to determine. This method can only determine the String type. 2. Use StringUtils.isEmpty(Object str); method to judge.
- JavaBase 3780 2019-11-21 16:11:10
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- What are the methods to determine whether a string is empty in java
- The methods to determine whether a string is empty in Java are: 1. Use the "equals()" method, for example: "if(s == null ||"".equals(s))"; 2. Compare the length of the string, For example: "if(s == null || s.length() <= 0)".
- JavaBase 3070 2019-11-21 15:58:49
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- How to determine the day of the week in java?
- How to determine the day of the week in java: You can use the DAY_OF_WEEK method provided in Calendar to get the day of the week. The date of the week obtained by DAY_OF_WEEK starts with Sunday.
- JavaBase 3416 2019-11-21 15:45:33
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- How to determine whether a character is a Chinese character in java
- The method to determine whether a character is a Chinese character in Java is: first use the "valueOf()" method to return the object value of the character, then define a regular expression for judgment, for example: "[\u4e00-\u9fa5]", and finally use Just match using the "matches()" method.
- JavaBase 6609 2019-11-21 15:42:10
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- How to determine whether the specified key exists in the map collection object in java
- Java's method of determining whether a specified key exists in a map collection object: first define a map object, then add objects to the collection through the "put()" method, then define a specified key value, and finally pass "map.containsKey()" Just use the method to judge.
- JavaBase 3850 2019-11-21 15:19:48
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- Java determines whether it is Chinese
- How to determine whether it is Chinese in java: 1. Use the regular expression "[\u4e00-\u9fa5]" to determine whether it is Chinese. 2. Determine whether the character is Chinese by judging whether the Unicode encoding of the character is between 19968 and 40869.
- JavaBase 3419 2019-11-21 15:15:47
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- How to determine whether data is ip in java
- The method to determine whether the data is IP in Java is: first determine whether the length of the data matches the IP length, then define a regular expression, use the "compile" method to compile the regular expression and create a matching pattern, and then use the "matcher()" method according to Just match the pattern.
- JavaBase 2683 2019-11-21 15:03:34
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- Java determines whether a string is a date
- How to determine whether a string is a date in Java: first specify the date format, and then use the DateFormat class or SimpleDateFormat class to determine whether it is the correct date format and whether it is a date.
- JavaBase 2974 2019-11-21 14:53:08
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- How to determine whether a string is in json format in java
- The method to determine whether a string is in json format in Java is: first format the string that needs to be processed, and then use the methods "startsWith()" and "endsWith()" to determine whether the first and last letters of the string are "{}" or "[]", if neither, it is not in json format.
- JavaBase 16319 2019-11-21 14:44:38
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- What collections are there in java
- There are three main types of collections in Java: set, list and map. List: stores ordered and repeatable elements, set: stores unordered and non-repeatable elements, map: stores elements in key-value form.
- JavaBase 4192 2019-11-21 14:35:33
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- How to determine whether a file is in xml format in java
- The method to determine whether a file is in XML format in Java is: first create a parser object through "DocumentBuilderFactory", then use the "parse()" method to parse the file, for example: "parse(file)", and finally make an exception based on the returned information Just judge.
- JavaBase 3890 2019-11-21 14:26:42
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- How to delete files in java
- In Java, you can use the file.delete(); method to delete files. When the delete() method is called, the file is deleted directly, regardless of whether the file exists, and it is executed immediately once called.
- JavaBase 15118 2019-11-21 14:19:58
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- How to determine whether a string is a url in java
- The method to determine whether a string is a URL in Java is: first use the string to set a regular expression, then compile the regular expression and create a matching pattern through the "Pattern.compile" method, and finally use the "matches()" method according to the matching pattern Just match the string.
- JavaBase 5775 2019-11-21 14:05:52
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- How to read files in java
- Methods for reading files in java: 1. Read by using the [java.io] method, relative to the relative path of the current user directory; 2. Read by using the [java.lang.ClassLoader] method, relative to the classpath The relative path to read.
- JavaBase 61223 2022-01-12 15:30:15
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- How to determine whether a number is prime (prime number) in java
- The method to determine whether a number is a prime number (prime number) in Java is: first determine whether the number is an even number, if so, return directly, and then start from the next number with a step size of 2 until the arithmetic square root of n. If it cannot be divided, it is a prime number.
- JavaBase 11391 2019-11-21 13:42:12
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