1. 下列代碼的執行結果是:
public class GoTest {
public static void main(String[] args) {
Sente a = new Sente();
();
Goban b = new Goban();
();
Stone c = new Stone();
();
}
}
class Sente implements Go {
public void go() {
tln(“go in Sente”);
}
}
class Goban extends Sente {
public void go() {
tln(“go in Goban”);
}
}
class Stone extends Goban implements Go {
}
interface Go {
public void go();
}
A. go in Goban
go in Sente
go in Sente
B. go in Sente
go in Sente
go in Goban
C. go in Sente
go in Goban
go in Goban
D. go in Goban
go in Goban
go in Sente
正確答案:C
2. A類中有一個方法:protected int print(String str){},B類繼承A類,以下方法能在B類中重寫A類中print()方法的是: ()。
A.
public int print(String str){}
B.
private int print(String str){}
C.
private void print(String str){}
D.
public void print(String str){}
正確答案:A
3. List類的對象list中的元素爲:[0, 1, 2, 3, 4, 5, 6, 7, 8, 9],現在想返回該list對象的子集合[5,6,7,8],需要做的操作是:
A. ist(5, 8);
B. ist(5, 9);
C. ist(4, 8);
D. ist(4, 9);
正確答案:B
4. 下列代碼的執行結果是:
String test = “Test A. Test B. Test C.”;
String regex = “.s*”;
String[] result = t(regex);
for (String s : result)
t(s + ” “);
A. Test A Test B Test C
B. Test A. Test B. Test C.
C. Test . Test . Test .
D. A. B. C.
正確答案:A
5.
執行下面的程序:
int a = 100;
int b = 200;
a = a + b;
b = a – b;
a = a – b;
tln(“a=” + a + “, b=” + b);
輸出的結果是:()。
A. a=100, b=300
B. a=100, b=200
C. a=200, b=100
D. a=300, b=200
正確答案:C
6.
類A,B和C的定義如下:
public class A {
public void f() {
tln(“A.f()”);
}
}
public class B extends A {
public void f() {
tln(“B.f()”);
}
}
public class C {
public void g(A a) {
tln(“g(A a)”);
a.f();
}
public void g(B b) {
tln(“g(B b)”);
b.f();
}
}
執行下面程序:
C c = new C();
A a = new B();
c.g(a);
輸出的結果是:()。
A. g(A a)
A.f()
B. g(A a)
B.f()
C. g(B b)
A.f()
D. g(B b)
B.f()
正確答案:B
7.
下列代碼編譯和執行的結果是()
public class Foo {
public static void main(String[] args) {
list = new yList();
(new B());
(new C());
for (A a : list) {
a.x();
a.y();
}
}
}
interface A {
void x();
}
class B implements A {
public void x() {}
public void y() {}
}
class C extends B {
public void x() {}
}
A.
代碼執行沒有輸出
B.
執行時拋出異常
C.
代碼a.y();行,編譯錯誤
D.
代碼 list = new yList();行,編譯錯誤