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How to determine whether an array is empty in java?

How to determine whether an array is empty in Java: directly use the if statement to determine whether the array is empty through "array==null", or use "array.length==0" to determine whether the array length is 0 to determine whether the array is empty.

Nov 19, 2019 pm 02:21 PM

java 数组

How to retain decimals in java

Methods for retaining decimals in java: 1. Use the API class BigDecimal provided in the java.math package to retain decimals. 2. Use DecimalFormat, a subclass of NumberFormat. 3. Use String.format. 4. Use NumberFormat.

Nov 19, 2019 pm 02:00 PM

java

How to use eclipse to generate java documentation

How to use eclipse to generate java documents: first go to the "generate javadoc" option under "project", then set the "javadoc" generation program, select the java project and document output directory to generate documents, and finally set the document encoding.

Nov 19, 2019 pm 01:55 PM

使用 eclipse java 文档

How to input in java?

Input methods in java: 1. Use the System.in.read() method to obtain input. 2. Use the BufferedReader class and the InputStreamReader class to obtain input. 3. Use the Scanner class to obtain input.

Nov 19, 2019 pm 01:44 PM

java

What are the methods to improve the performance of java programs?

Methods to improve the performance of Java programs include: 1. Try to specify the final modifier of the class; 2. Try to reuse objects; 3. Try to use local variables; 4. Do not initialize variables repeatedly; 5. When using synchronization mechanisms, try to use method synchronization instead of code. Block synchronization.

Nov 19, 2019 pm 01:42 PM

提高 java 程序性能

How to solve Chinese garbled characters in Java?

Solution to Chinese garbled characters in Java: 1. Set the encoding format of the Java editor. This method can change the encoding of all projects. 2. Set the project code. This method modifies the code of a single project. 3. Set the encoding of a single file.

Nov 19, 2019 pm 01:31 PM

java

How to install mobile java program

How to install java program on mobile phone: first download the mobile version of java simulator; then open the simulator and select the location of the java program, and the simulator will automatically install the java program; finally click the start button to open the program.

Nov 19, 2019 pm 01:24 PM

java 手机安装

Determine whether a string is a number in java

How to determine whether a string is a number in java: 1. Use the method Character.isDig(char ch) that comes with java to determine. 2. Use the regular expression "-?[0-9]+(\\.[0-9]+)?" to determine whether the string is a number.

Nov 19, 2019 pm 01:21 PM

java 字符串

Determine whether a file or folder exists in java

The method to determine whether a file or folder exists in Java is: You can use the "file.exists()" or "file.isDirectory()" method to determine whether the file or folder exists. If the file or folder exists, it will return true, otherwise it will return false.

Nov 19, 2019 am 10:49 AM

java 判断文件文件夹存在

How to determine whether strings are equal in java

The method to determine whether strings are equal in Java is: You can use the "equals(object obj)" method to determine, for example: "a.equals(b)". If a and b are equal, it will return true, otherwise it will return false.

Nov 19, 2019 am 09:37 AM

java 判断字符串相等

How to assign values to arrays in java

The method of assigning values to arrays in Java is: 1. Use "==" to assign values. At this time, the new array points to the storage space of the original array without re-applying for new space; 2. Use the "System.ararycopy" method to re-apply for the new array. storage space, and then copy the data in the original array.

Nov 18, 2019 pm 05:34 PM

java 数组赋值

How to create an array in java

The methods of creating an array in Java are: 1. Declare and assign a value, such as: "int[] arr = {1,2,4, ...}"; 2. Declare the array name to open up space and assign a value, such as: "int[] arr ;arr = new int[]{1,2,3,…}”.

Nov 18, 2019 pm 05:21 PM

java 数组创建

The difference between inheritance and implementation in java

The difference between inheritance and implementation in Java is: 1. The modifier of implementation is "implements", and the modifier of inheritance is "extends"; 2. When an interface is implemented by a class, the abstract method in the interface must be implemented in the class, and Inheritance can call methods at will.

Nov 18, 2019 pm 05:05 PM

java 继承实现区别

The difference between static methods and instance methods in java

The difference between static methods and instance methods in Java is: when static methods access members of this class, they are only allowed to access static members, and are not allowed to access instance member variables and instance methods, but instance methods do not have this restriction.

Nov 18, 2019 pm 04:43 PM

java 静态方法实例方法区别