){return x - y;}},TIMES("*"){double apply(double x,double y){return x * y;}},DIVIDE("/"){double apply(double x,double y){return x / y;}};private final String symbol;Operation(String symbol){this.symbol = symbol;}@Overridepublic String toString(){return symbol;}abstract double apply(double x,double y);}
Run as Java Application,we can see the console.the result shows operations?
1234
2.000000 + 4.000000 = 6.0000002.000000 -
As a Java programmer, the most painful thing is to choose too wide, can read too many books, often easily confused. I would like to choose some of the technical books I have read, according to the Order of study, recommend to everyone, especially those who want to constantly improve their technical level of Java programmers. In addition, you can join 457036818 Exchange groups and share your knowledge about
Java programmer's Advanced Path-developed by senior java programmers and java programmers
1. Introduction
Java developers certainly want to reach a higher level, use less code to solve more problems, and use a clearer structure to prepare for possible inheritance and maintenance. Think about the learning routes that ma
Learning plan diagram of actual Java Virtual Machine (Understand Java Virtual Machine), Java Virtual Machine
I don't want to talk about it anymore. I am actually using a Java virtual machine. I have to study hard and get started every day! Develop a learning plan for your weaknesses.
After reading some of the content
In general, the data structures on textbooks include arrays, single-linked lists, stacks, trees, and graphs. The data structure I'm referring to here is a question of how to represent an object, and sometimes a single variable declaration can be overwhelming, such as a int,string,double or even a one-dimensional array, a two-dimensional array that cannot fully express what you are expressing, and defining a class is too troublesome You can consider using the collections class in
1. Write a program to copy all the. java files from the D: \ java directory to the D: \ Jad directory and change the original file extension from. java to. jadPackage Copy;import Java.io.bufferedinputstream;import java.io.bufferedoutputstream;import java.io.File;import Java.io.fileinputstream;import Java.io.fileoutputstream;import Java.io.filenamefilter;import ja
Author: Xiaolou
Original Website:
Http://blog.vonno.com/33993/viewspace_1245
17:50:57/personal classification: Knowledge Summary
Cause:An exception occurs when a Java program is used to query a large amount of data from the database:Java. Lang. outofmemoryerror: Java heap SpaceThis exception is thrown if 98% is used for GC and the available heap size is less than 2% in JVM.JVM heap setting refers to the se
Tree-like Java model, hierarchical relational Java model, hierarchical relational Java model and HTML page displayFirst, the business prototype: the company's organizational structure, marketing NetworkSecond, the database modelVery simple, create ID and PID relationship can be. (pid:parent_id)Third, Java model( We sca
Java technology _ Java 0021 _ What is an exception in java?1. What is a java exception? java has encountered some problems during execution, resulting in execution interruption. This problem is called an exception.Exceptions may occur for different causes, including:= Invali
Java learning notes: Java Process Control and java learning notesI. Introduction
Java Process Control includesSequential Control, condition control, and cyclic control.
Sequential control means that each statement is executed from start to end in sequence. Conditional Control: select the execution statement based on th
Java solution: Java compiler level does not match the version of the installed Java project facet., compilerfacet
Cause: the Java compiler level does not match the Java version settings in the Facted Project.
Solution: Set the two in the same way.
1. View
Where is 1.Java Build pathUnder the properties of the right mouse button of the project, or in the Java of Window's properties2. There are two options for project and folderProject: In ProjectsFolder: In folders, there are two places to fill inSOURCE folder name: Build directory to search SRCDefault output folder or output folder name: Compiled output directory binBuild path for 3.javaSearch under SRC, the
At present, there are "Java xx book" Similar books, and the contents of the book are focused on the most basic part of Java, the most serious is that there is a lot of wrong content, very misleading. In addition, there are a variety of Java interview questions on the web, many of which are also focused on the Java lang
/** * Write a program to copy all the. java files in the D:\java directory to the D:\jad directory and change the extension of the original file from. java to. jad.
* *: The Listfiles method accepts a FileFilter object, the FileFilter object is the policy object of the filter, and different people provide different filefilter implementations, that is, different
Struts2: java. lang. NoSuchFieldException: resourceEntries at java. lang. Class. getDeclaredField (Class. java: 1901), resourceentries
During the Struts2 test case today, the program can jump normally, but an error is reported on the Console, as shown below:
1 java.lang.NoSuchFieldException: resourceEntries 2 at java.lang.Class.getDeclaredField(Class.java:
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JAVA basics/Lesson 24th: What does THIS mean in classes and objects/JAVA? Passing parameter xiangjie and java xiangjie
1. the keyword "this" is equivalent to "I" in Mandarin, for example:
When James says "I have eaten", "I" represents JamesWhen Xiaohong says "I have eaten", "I" represents Xiaohong."I" represents the current character.
1. this indicates the curre
JAVA basics/Lesson 22nd: classes and objects/What are references in JAVA? Inherit ?, Java inheritance
1. The concept of reference. If a variable is of the class type rather than the basic type, this variable is also called a reference.
1. Reference and point:
new Hero();
Creates a Hero object.But it only creates an object and cannot be accessed.To access this ob
Recalling Java memoirs (2): Java 02 class and object, Java 02
Class: subjective abstraction. Object Templates Can be instantiated into objects-defining a template, which cannot be directly used.
--- To use classes, you must create them as objects.
-- Abstract The actual objects (emphasize the similarities between objects and ignore different processes)
-- Use a
20.1 Java New IO Introduction20.2 Buffers with BufferExample: demonstrating the operation flow of buffersClass:intbufferdemo0120.2.2 Deep buffer operation20.2.3 Creating a sub-buffer20.2.4 creating a read-only buffer20.2.5 Creating a direct buffer20.3 Channels20.3.1 FileChannelExample: Using output channels to output contentClass:filechanneldemo01Example: Using a channel for read and write operationsClass:filechanneldemo0220.3.2 Memory MappingExample:
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