多选题 Consider the interface CharSequence that is a required argument in one of the replace method declarations:
public String replace(CharSequence target, CharSequence replacement) {
...
}
This CharSequence interface is a super interface to which concrete classes?
  • A. String
  • B. StringBoxer
  • C. StringBuffer
  • D. StringBuilder
【正确答案】 A、C、D
【答案解析】具体的类String、StringBuffer和StringBuilder全都实现了接口CharSequence。这些类都能够以多态的方式用于String类的replace方法,因为它期望的参数是CharSequence。B不正确。没有StringBoxer这样的类。