一、Java 在Web开发中的优势
Java
首先,Java
public class Hello{ public static void main(String args[]){ System.out.println("Hello World"); } }
这段代码中的Java
其次,Java
Java
最后,Java
Java
二、Java 在移动应用开发中的优势
Java
首先,Java
Java
其次,Java
Java
最后,Java
Java
三、Java 在大数据处理中的优势
Java
首先,Java
Java
public class WordCount{ public static void main(String[] args) throws Exception{ String inputFile = "hdfs://localhost:9000/input/file01.txt"; String outputFile = "hdfs://localhost:9000/output"; Configuration conf = new Configuration(); Job job = Job.getInstance(conf, "WordCount"); job.setJarByClass(WordCount.class); job.setMapperClass(TokenizerMapper.class); job.setCombinerClass(IntSumReducer.class); job.setReducerClass(IntSumReducer.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); FileInputFormat.addInputPath(job,new Path(inputFile)); FileOutputFormat.setOutputPath(job,new Path(outputFile)); System.exit(job.waitForCompletion(true) ? 0 : 1); } } class TokenizerMapper extends Mapper
这段程序用MapReduce模式,实现了简单的单词计数,处理的是一个文件夹中所有的.txt文件。
其次,Java
Java
public class FileList{ public static void main(String[] args) throws Exception{ String folderPath = "/home/work/data/"; File folder = new File(folderPath); File[] listOfFiles = folder.listFiles(); for (int i = 0; i < listOfFiles.length; i++) { if (listOfFiles[i].isFile()) { System.out.println("File " + listOfFiles[i].getName()); } else if (listOfFiles[i].isDirectory()) { System.out.println("Directory " + listOfFiles[i].getName()); } } } }
这段程序使用了Java的File类,遍历指定文件夹下的所有文件和目录。
最后,Java
Java
四、Java 在企业级应用开发中的优势
Java
首先,Java
Java
其次,Java
Java
public class Employee{ private int id; private String name; private String email; private double salary; public Employee() {} public Employee(int id, String name, String email, double salary){ this.id = id; this.name = name; this.email = email; this.salary = salary; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public double getSalary() { return salary; } public void setSalary(double salary) { this.salary = salary; } } public interface EmployeeDao { public ListgetAllEmployees(); public void addEmployee(Employee employee); public void updateEmployee(Employee employee); public void deleteEmployee(int id); } public class EmployeeDaoImpl implements EmployeeDao{ List employees; public EmployeeDaoImpl(){ employees = new ArrayList (); employees.add(new Employee(1,"John","john@gmail.com",5000)); employees.add(new Employee(2,"Lily","lily@gmail.com",6000)); employees.add(new Employee(3,"Mike","mike@gmail.com",7000)); } public void deleteEmployee(int id) { for(Employee employee : employees){ if(employee.getId() == id){ employees.remove(employee); break; } } } public List getAllEmployees() { return employees; } public void addEmployee(Employee employee) { employees.add(employee); } public void updateEmployee(Employee employee) { for(Employee emp : employees){ if(emp.getId() == employee.getId()){ emp.setName(employee.getName()); emp.setEmail(employee.getEmail()); emp.setSalary(employee.getSalary()); break; } } } }
这是一个企业级应用程序中的Java
最后,Java
Java
五、Java 在计算机科学教育中的优势
Java
首先,Java
Java
public class HelloWorld{ public static void main(String[] args){ System.out.println("Hello, World!"); } }
这段代码便是Java
其次,Java
Java
最后,Java
Java
结语
以上便是Java