java开发的CS标准考试系统

ACD 1:20:50 Which interface does java.util.Hashable implement? A. java.util.Map B. java.util.List C. java.util.Hashable D. java.util.Collection ** Given: 1. public class X { 2. public object m () { 3. object o = new Float (3.14F); 4. object [] oa = new object [1]; 5. oa[0]= o; 6. o = null; 7. oa[0] = null; 8.return o; 9. } 10. } When is the float object created in line 3, eligible for garbage collection? A. Just after line 5 B. Just after line 6 C. Just after line 7 D. Just after line 8(that is, as the method returns) ** Given: 1. public class returnIt ( 2. returnType methodA(byte x, double y) ( 3. return (short) x/y * 2; 4. ) 5. ) What is the valid returnType for methodA in line 2? A. int B. byte C. long D. double