java “错误：无法找到或加载主类 My.class”
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"Error: Could not find or load main class My.class"
提问by James Milner
Im using Java SDK 1.7 on Windows 7 via cmd.exe . Up until a few hours ago everything was working correctly when suddenly I was unable to run my compiled class files, consistently presented with the error in the title.
我通过 cmd.exe 在 Windows 7 上使用 Java SDK 1.7。直到几个小时前，一切都正常工作，突然我无法运行我编译的类文件，标题中始终出现错误。
I seem to be able to compile my My.java file however I am unable to run the resulting class file (My.class). I am constantly given the error "Error: Could not find or load main class My.class". I have tried this with multiple other class files all resulting in the same problem.
我似乎能够编译我的 My.java 文件，但是我无法运行生成的类文件 (My.class)。我经常收到错误“错误：无法找到或加载主类 My.class”。我已经用多个其他类文件尝试过这个，都导致了同样的问题。
My 'Path' environment variable is set to "C:\Program Files (x86)\Java\jdk1.7.0_05\bin" if you were wondering
如果您想知道，我的“路径”环境变量设置为“C:\Program Files (x86)\Java\jdk1.7.0_05\bin”
I have tried reinstalling, creating and setting a classpath variable (no luck), and even directly using the
我试过重新安装、创建和设置类路径变量（没有运气），甚至直接使用
java -cp . My.class
java -cp . My.class
command.
命令。
I have tried these posts all to no avail, hence why I'm posting:
我已经尝试过这些帖子都无济于事，因此我为什么要发布：
Error: Could not find or load main class
Error: Could not find or load main class- Novice
Could not find or load main class
Java 1.7.0_03 Error: Could not find or load main class
If it makes any difference my code is :
如果它有任何不同，我的代码是：
import javax.swing.JOptionPane;
class My {
public static void main(String[] args) {
final double x = 3.2;
int i = (int)x;
double m = 0;
if (x < 4) {
String saySomething = JOptionPane.showInputDialog(i);
System.out.println(saySomething);
}
else {
String saySomething = JOptionPane.showInputDialog(i);
System.out.println("Hello World");
}
while (m < 10) {
System.out.print(" While Loop ");
m++;
};
for (i=1; i < 10; i++) {
System.out.println("For Loop");
};
}
}
回答by user268396
You should specify the classname instead of the file of the class to load. The difference is a simple matter of removing the .classextension.
您应该指定类名而不是要加载的类的文件。区别在于删除.class扩展名的简单问题。
回答by Peter Lawrey
I would use an IDE and you shouldn't get these issues. Compile and run is just a click of the mouse.
我会使用 IDE，你不应该遇到这些问题。只需单击鼠标即可编译和运行。
BTW to run your program from the command line
顺便说一句，从命令行运行你的程序
java -cp . My
You don't add .class
你不加 .class
回答by ioreskovic
Position yourself in a directory of your project (you need to have src and bin directories there, assuming you keep sources in src and binaries in bin)
将自己放在项目的目录中（假设您将源代码保存在 src 中，二进制文件保存在 bin 中，您需要在那里有 src 和 bin 目录）
java -cp bin My
回答by Vikas Dhyani
I myself was facing the same problem. It was happening because I was being remiss in typing the name of the class properly. In my instance, I was typing
我自己也面临着同样的问题。之所以发生这种情况，是因为我在正确键入课程名称时疏忽了。在我的例子中，我正在打字
java doubler
java倍增器
instead of
代替
java Doubler
java倍增器
