ToolProvider.getSystemJavaCompiler() always returning null using jdk

问题

I read all the posts regarding this problem and no solution works for me, I get always null.

I use JRE and put the tools.jar in the lib directory, added it to the build path but when I want to jump to declaration Eclipse wants to jump into rt.jar (?) what I totally don't understand.
Could that be the reason that I get only null? How can I configure that correctly?

What are the criteria for getSystemJavaCompiler() to return null?

Preferences screenshot

回答1:

JRE is the Java Runtime Environment. It doesn't have a compiler, and therefore you're getting a null. If you use a full-fledged JDK, you'd get a non-null result.

回答2:

I found a workaround for my problem. First I used the jre again. I put the tools.jar in the lib directory of the application.
ToolProvider.getSystemJavaCompiler() return null.
This is the workaround to get the JavaCompiler:

JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
if (compiler == null){
    try {
        Class<?> javacTool = Class.forName("com.sun.tools.javac.api.JavacTool");
        Method create = javacTool.getMethod("create");
        compiler = (JavaCompiler) create.invoke(null);
    } catch (Exception e) {
        throw new AssertionError(e);
    }

来源：https://stackoverflow.com/questions/46096598/toolprovider-getsystemjavacompiler-always-returning-null-using-jdk