Java single inheritance questions

There are few structures in Java that are not so intuitive as others. Take a look:

public class InnerInvocation {

 String getValue() {
  return "Outer Value";
 }

 private class InnerClass {
  String getValue() {
   return "Inner Value";
  }

  void work() {
   // insert code here
  }
 }
}

What code do you need to invoke getValue() method from outer class?

Here is the answer:

  void work() {
   InnerInvocation.this.getValue();
  }

And now the question of the day: there is syntax that possibly can allow multiple inheritance in Java, so why is it forbidden? Because you as developer can make lots of mistakes? Why then they allowed reflections?