java - 使用 JavaCompiler 时出现 Nullpointerexception 错误

Question

以下是用eclipse ide编写的java代码...

package compile;

import java.io.IOException;
import java.util.Arrays;
import javax.tools.DiagnosticCollector;
import javax.tools.JavaCompiler;
import javax.tools.JavaFileObject;
import javax.tools.StandardJavaFileManager;
import javax.tools.ToolProvider;

public class Execute {
    public static void main(String args[]) throws IOException, ClassNotFoundException {
        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
        DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();
        StandardJavaFileManager fileManager = compiler.getStandardFileManager(
                diagnostics, null, null);
        Iterable<? extends JavaFileObject> compilationUnits = fileManager
                .getJavaFileObjectsFromStrings(Arrays
                        .asList("F:\\practice java\\project\\KeepingMoreKidsQuiet.java"));
        JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager,
                diagnostics, null, null, compilationUnits);
        boolean success = task.call();

        System.out.println(success);
        if(!success)
            System.out.println(diagnostics.getDiagnostics());
        fileManager.close();
    }
}

当我运行我的 Java 程序时，它在这一行给我一个错误

StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnostics, null, null);

我得到的错误是:

Exception in thread "main" java.lang.NullPointerException at compile.Execute.main(Execute.java:17)

你能告诉我如何解决这个错误吗？

Answer 1

来自 ToolProvider.getSystemJavaCompiler() :

Returns:

the compiler provided with this platform or null if no compiler is provided