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- How to use java class library
- Take using the Math class library to write an arithmetic square root program as an example: 1. First open the official java online API document; 2. Check the usage of the sqrt function of the Math class library in the [Java API] document; 3. Write the java code, and Just run the program.
- JavaBase 3173 2020-02-03 10:14:57
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- Pictures in java project cannot be displayed
- The solution to the problem that pictures cannot be displayed in Java projects is: 1. First check whether there is a problem with the path of the picture, whether an absolute path is used, and if so, change it to a relative path; 2. If a relative path is used and the path is checked, but If the image still cannot be displayed, you can add [../] in front of the path.
- JavaBase 5032 2020-02-03 09:29:59
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- The system prompts javac: file not found
- The system prompts javac: the file cannot be found. The solution is: 1. First enter the directory where the java file is located, such as [cd eclipse\project]; 2. Then execute the [javac file name.java] command, such as [javac dictionray2_0. java].
- JavaBase 4459 2020-03-09 18:40:09
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- Unable to install java runtime environment jre
- The solution to the failure to install the java runtime environment jre is: 1. First open the run window, enter [services.msc] to open the service; 2. Then find the [windows installer] service and open the property configuration; 3. Finally start the service .
- JavaBase 6289 2020-02-02 21:12:29
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- How to understand java architecture
- In the development of javaEE, almost all are developed based on the B/S architecture. In this architecture, the system and standard three-layer architecture include: presentation layer, business layer, and persistence layer. The presentation layer is responsible for receiving client requests, the business layer is responsible for processing business logic, and the persistence layer is responsible for data persistence.
- JavaBase 3075 2020-02-02 21:00:13
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- What will happen if the io stream is not closed in java?
- If the io stream is not closed, the system resources cannot be released, because when we create a new Java stream object, not only an instance object of the corresponding class is created in the computer memory, but also the corresponding system resources are occupied, such as: File handles, ports, database connections, etc.
- JavaBase 5223 2020-02-01 20:57:25
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- What does the parameter '...' mean in java
- The writing method of parameter "..." in Java is a new way of writing method parameters, called a variable length parameter list, such as [Object...os], which means that the parameters accepted here are from 0 to more Object types. Object, or an [Object[]].
- JavaBase 4729 2020-02-01 20:45:01
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- Chinese garbled characters appear when eclipse imports java projects
- The solution to Chinese garbled characters when importing Java projects into eclipse is: 1. First check the encoding format of the java file; 2. Then open the eclipse property settings panel and open the [content types] option; 3. Finally, modify the default encoding format of the java file. .
- JavaBase 3031 2020-01-16 10:11:41
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- Can static properties and static methods in Java be inherited?
- Static properties and static methods in Java can be inherited, but they are not overwritten, but hidden. Static methods and static attributes belong to classes, and can be called directly through [class name.method name], and they can be called without the need for an inheritance mechanism.
- JavaBase 3558 2020-01-16 09:52:34
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- Java determines whether a string is an integer number
- The method for Java to determine whether a string is an integer is: 1. First define a specified pattern for judgment; 2. Then create a [pattern] object; 3. Finally create a [matcher] object and perform the process according to the specified pattern. Just judge.
- JavaBase 3509 2020-01-16 09:34:06
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- The difference between proxy pattern and decorator pattern in java
- The difference between the proxy mode and the decorator mode in Java is: the decorator mode dynamically attaches responsibilities to the decorated object to extend the function of the object; the proxy mode is to proxy other objects to control the proxy. Object access.
- JavaBase 2267 2020-01-15 16:52:12
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- Java determines whether the specified object exists in the map
- In Java, you can use the containsValue method to determine whether the map contains the specified object. Returns true if this map maps one or more keys to the specified value.
- JavaBase 2551 2020-01-14 14:14:27
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- What data structures are there in java
- The data structures in Java include: Enumeration, BitSet, Vector, Stack, Dictionary, Hashtable, Properties, etc.
- JavaBase 8876 2020-01-14 13:58:24
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- Can abstract classes in java be inherited?
- Abstract classes in java can be inherited. An abstract class is just a special class, but it also has the characteristics of a class. If there are abstract methods in this class, then this class must be defined as an abstract class.
- JavaBase 5910 2020-01-14 13:45:37
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- Can map in java be sorted based on key?
- Maps in java can be sorted according to key. There are two commonly used sorting methods for maps in Java, namely sort by key and sort by value.
- JavaBase 4229 2020-01-14 13:32:51