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What does java if(x) mean?

The meaning of java if(x) is that when the value of variable x is not empty, not 0, not false, not null, the following content will be executed.

Nov 18, 2019 pm 01:38 PM

java if

Java determines whether list contains a certain value

Java method to determine whether a list contains a certain value: You can use the "contains(Object o)" method, which is used to determine whether the list contains a specified element. If the list contains the specified element, it returns true, otherwise it returns false. .

Nov 18, 2019 pm 01:26 PM

java list 包含

What is the length of java int?

java int is 4 bytes, 32 bits, and the value range is -2^31—2^31-1, that is, the length is -2147483648—2147483647.

Nov 18, 2019 pm 01:24 PM

java int 长度

The difference between list and arraylist in java

The difference between List and ArrayList in Java is: List is an interface, and ArrayList is an implementation class of the List interface. The ArrayList class inherits and implements the List interface.

Nov 18, 2019 pm 01:17 PM

java list arraylist 区别

where is java jdk

Java jdk is installed in the C:\Program Files\Java\ directory by default. You can open cmd and enter "java -version" to view the specific path; on Linux systems, you can use the which java command to view it.

Nov 18, 2019 pm 01:08 PM

java jdk 路径

Is the key sorting of java map?

The keys of HashMap and HashTable in java map are not sorted, and the data is fetched randomly; the keys of LinkedHashMap and TreeMap are sorted, and the output is in the order of storage and ascending order during traversal.

Nov 18, 2019 am 11:46 AM

java map key 排序

What does the import keyword mean in java

The import keyword in java is used to import packages. If a class is used in a class from another package, it needs to be introduced using the import keyword, for example: "java.util.*", which means to import all classes or interfaces under the util package.

Nov 18, 2019 am 11:38 AM

java import 关键字

The difference between java map and list

The differences between java map and list are: 1. Map is a collection that maps key objects and value objects, and elements cannot be repeated; 2. List stores objects in a linear manner, and elements can be repeated; 3. List uses the add method to add elements ;4. Map uses the put method to add elements, and so on.

Nov 18, 2019 am 11:24 AM

java map list

How to get out of for loop in java

The method for Java to jump out of a for loop is: if it is a single-layer loop, use break to jump out normally; if it is a multi-layer loop, you can give the for loop a name. The naming rule is name + half-width colon, and then use break followed by the name. You can jump out of the for loop.

Nov 18, 2019 am 11:14 AM

java 跳出 for 循环

java socket garbled code

The solution to Java socket garbled code: first use InputStreamReader on the server to specify the client's input stream as utf-8 encoding, and use OutputStreamWriter to specify the output stream as utf-8 encoding; then set the same utf-8 encoding on the client.

Nov 18, 2019 am 11:05 AM

java socket 乱码

What does '...' mean in java

The symbol "..." in Java represents a variable-length parameter, which means that any number of parameters of this type can be passed in at this position. For example, if used in a formal parameter, it means that the number of parameters passed in is variable. The parameters passed in are put into an array.

Nov 18, 2019 am 11:00 AM

java ... 意思

How to write java sql statement

How to write a java sql statement: first write the sql statement prototype; then change the required value to double single quotes; then add double quotes between the single quotes; then add two + signs between the double quotes; finally Just write the variable in the plus sign.

Nov 18, 2019 am 10:51 AM

java sql 怎么写

The difference between >>> and >> in java

The difference between ">>>>" and ">>" in Java is: ">>" means right shift. If the number is positive, the high bits are filled with 0. If it is a negative number, the high bits are filled with 1; ">>>>" means Unsigned right shift. If the number is positive, the high bits are filled with 0. If the number is negative, the high bits are also filled with 0 after the right shift.

Nov 18, 2019 am 10:44 AM

java >>> >> 区别

java string garbled characters

Solution to garbled java string: 1. Use "new String(str.getBytes("ISO-8859-1"), "utf-8")" to convert the string to utf-8 encoding; 2. Use "URLDecoder. decode" to transcode the url.

Nov 18, 2019 am 10:22 AM

java string 乱码