我正在尝试从Windows中的命令行执行Java程序。这是我的代码:

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class CopyFile
{
    public static void main(String[] args)
    {

        InputStream inStream = null;
        OutputStream outStream = null;

        try
        {

            File afile = new File("input.txt");
            File bfile = new File("inputCopy.txt");

            inStream = new FileInputStream(afile);
            outStream = new FileOutputStream(bfile);

            byte[] buffer = new byte[1024];

            int length;
            // copy the file content in bytes
            while ((length = inStream.read(buffer)) > 0)
            {

                outStream.write(buffer, 0, length);

            }

            inStream.close();
            outStream.close();

            System.out.println("File is copied successful!");

        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }
}

我不知道如何执行这个程序——有什么帮助吗?这在Windows上可行吗?为什么它与其他环境不同(我以为JVM是一次编写,随处运行)?


当前回答

现在(从JDK 9开始),您可以使用java来执行该命令。 为了执行包含main的"Hello.java",可以使用: java Hello.java

你不再需要单独使用javac进行编译。

其他回答

现在(从JDK 9开始),您可以使用java来执行该命令。 为了执行包含main的"Hello.java",可以使用: java Hello.java

你不再需要单独使用javac进行编译。

来源:javaindos。

Let's say your file is in C:\mywork\ Run Command Prompt C:\> cd \mywork This makes C:\mywork the current directory. C:\mywork> dir This displays the directory contents. You should see filenamehere.java among the files. C:\mywork> set path=%path%;C:\Program Files\Java\jdk1.5.0_09\bin This tells the system where to find JDK programs. C:\mywork> javac filenamehere.java This runs javac.exe, the compiler. You should see nothing but the next system prompt... C:\mywork> dir javac has created the filenamehere.class file. You should see filenamehere.java and filenamehere.class among the files. C:\mywork> java filenamehere This runs the Java interpreter. You should then see your program output. If the system cannot find javac, check the set path command. If javac runs but you get errors, check your Java text. If the program compiles but you get an exception, check the spelling and capitalization in the file name and the class name and the java HelloWorld command. Java is case-sensitive!

完整回答:

The Java File TheJavaFile.java Compile the Java File to a *.class file javac TheJavaFile.java This will create a TheJavaFile.class file Execution of the Java File java TheJavaFile Creation of an executable *.jar file You've got two options here - With an external manifest file : Create the manifest file say - MANIFEST.mf The MANIFEST file is nothing but an explicit entry of the Main Class jar -cvfm TheJavaFile.jar MANIFEST.mf TheJavaFile.class Executable by Entry Point: jar -cvfe TheJavaFile.jar <MainClass> TheJavaFile.class To run the Jar File java -jar TheJavaFile.jar

从Java 9开始,JDK包含了jshell,一个Java REPL。

假设JDK 9+ bin目录被正确地添加到您的路径中,您将能够简单地:

运行jshell file .java - file .java当然是你的文件。 将打开一个提示符,允许您调用main方法:jshell> File.main(null)。 要关闭提示符并结束JVM会话,请使用/exit

JShell的完整文档可以在这里找到。

编译一个Java文件来生成一个类:

javac filename.java

执行生成的类:

java filename