• 2022-06-06
    以下接口定义错误的是( )。
    A: interface Singer
    { void sing();}
    B: abstract interface Singer
    { void sing(){ };}
    C: interface Singer extends S1 // S1是已定义的接口
    { void sing();}
    D: interface Singer extends S1, S2 //S1、S2为已定义的接口
    { abstract void sing();}