关于java8向后兼容性的问题:JDK中的新方法

简单的问题。在Java8中,JDK类中有大量的新方法。假设我们使用Java 7(或Java 6)创建了这样的类:

class MyArrayList<E> extends ArrayList<E> {
        public void sort(Comparator<E> c) {
            // some sort
        }
}

这是相当合理的实施。现在我们尝试用Java 8编译它,并收到预期的编译错误:

error: name clash: sort(Comparator<E#1>) in MyArrayList and sort(Comparator<? super E#2>) in ArrayList have the same erasure, yet neither overrides the other
            public void sort(Comparator<E> c) {
                        ^   where E#1,E#2 are type-variables:
    E#1 extends Object declared in class I.MyArrayList
    E#2 extends Object declared in class ArrayList

在此,我想提出两个问题:

1. 即使有 javac -source 1.7 -target 1.7 使用JDK 8的选项我收到 相同的 错误-为什么?我认为这些选项应该允许编译遗留代码。

2. 一般来说向后兼容性如何?

编辑 准确地说,可能是我做错了什么?JDK 1.8.0_65,Mac OS X:

bash-3.2$ javac -version
javac 1.8.0_65
bash-3.2$ javac -source 1.7 -target 1.7 MyArrayList.java 
warning: [options] bootstrap class path not set in conjunction with -source 1.7
MyArrayList.java:7: error: name clash: sort(Comparator<E#1>) in MyArrayList and sort(Comparator<? super E#2>) in ArrayList have the same erasure, yet neither overrides the other
    public void sort(Comparator<E> c) {
                ^
  where E#1,E#2 are type-variables:
    E#1 extends Object declared in class MyArrayList
    E#2 extends Object declared in class ArrayList
1 error
1 warning