java - 可以在 java 程序中运行 java 类吗？

Question

我一直在创建一个编写和运行 java 类的程序。到目前为止，我已经能够编写“Runable.java”类，但无法运行它。我尝试运行“runjava.bat”并让 .bat 运行“Runable.java”类，但我不断收到“错误:无法找到或加载主类 application.Runable.class”。我想知道我做错了什么，或者是否有更好的方法从 java 程序中运行 java 类？

这是我的代码(稍微简化):

Main.java:

package application;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;

import javafx.application.Platform;
import javafx.stage.FileChooser;


public class Main {
final static String Program =
        "package application;\n"
        + "public class Runable {\n"
        + "public static void main(String[] args) {\n"
        + "System.out.println(\"Hello\");\n"
        + "}\n"
        + "}\n";

public static void main(String[] args) throws IOException {
    Scanner s = new Scanner(System.in);
    while(true){
    System.out.println("State a comand.");
    String Command = s.nextLine();
    if (Command.equalsIgnoreCase("Write") || Command.equalsIgnoreCase("Save")){
         FileChooser fileChooser = new FileChooser();

         //Set extension filter
         FileChooser.ExtensionFilter extFilter = new FileChooser.ExtensionFilter("TXT files (*.txt)", "*.txt");
         fileChooser.getExtensionFilters().add(extFilter);

         //Show save file dialog
         File file = new File("src/application/Runable.class");

         if(file != null){
             SaveFile(Program, file);
         }

    }
    else if (Command.equalsIgnoreCase("Run") || Command.equalsIgnoreCase("Play")){
        ProcessBuilder builder = new ProcessBuilder(
                "src/runjava.bat");
            builder.redirectErrorStream(true);
            Process p = builder.start();
            BufferedReader r = new BufferedReader(new InputStreamReader(p.getInputStream()));
            String line;
            while (true) {
                line = r.readLine();
                if (line == null) { break; }
                System.out.println(line);
            }
    }
    else if (Command.equalsIgnoreCase("End") || Command.equalsIgnoreCase("Exit")){
        Platform.exit();
    }
    else{
        System.err.println("Command not recognized.");
        System.err.println("Please try again.");
    }
    }

}

private static void SaveFile(String content, File file){
    try {
        FileWriter fileWriter = null;

        fileWriter = new FileWriter(file);
        fileWriter.write(content);
        fileWriter.close();
    } catch (IOException ex) {
        Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
    }

}


}

runjava.bat:

javac "src\application\Runable.java"
java application.Runable.class

和Runable.java(如果您没有从 Main.java 获取它):

package application;
public class Runable {
public static void main(String[] args) {
System.out.println("Hello");
}
}

Answer 1

java 命令需要类名，而不是文件名。除非你的类在“application.Runable”包中被称为“class”(它不是)，否则你可能想使用:

java application.Runable