B 2.String s = new String("xyz");创建了几个StringObject?
A:两个或者一个都有可能
B:两个
C:一个
D:三个
D 3,下列代码的输出是什么?
public static void main(String[] args) {
StringBuffer a = new StringBuffer("A");
StringBuffer b = new StringBuffer("B");
change(a, b);
System.out.println(a+","+b);
}
public static void change(StringBuffer x,StringBuffer y) {
x.append(y);
y = x;
}
D 8.以下程序的输出结果
class Base {
public Base(String s) {
System.out.println("B");
}
}
public class Dervid extends Base {
public Dervid(String s) {
System.out.println("D");
}
public static void main(String[] args) {
System.out.println("C");
}
}
A:BD
B:DB
C:C
D:编译错误
D 6.执行下列代码会发生什么?
public class Test {
static {
int x = 5;
}
static int x,y;
public static void main(String[] args) {
x--; //x=-1
myMethod();
System.out.println(x+y+ ++x);
}
public static void myMethod() {
y = x++ + ++x;
}
}
A:编译出错
B:输出1
C:输出2
D:输出3
E:输出7
F:输出8