2019年Java笔试题及答案.doc

2019年Java笔试题及答案.doc给出以下代码
public class Switchl{
final static short x=2;
public static int y=0;
public static void main(String[] args) {
for (int z=0;z<4;z++){
switch(z) (
case x:System, out. print ( "0”);
default:System, out. print ( "def");
case x~l:System, out. print ( "1" ) ;break;
case x~2:System, out. print ( "2”);
}
}
}
}
class ParentClass(
public int doStuff(int x){
return x*2;
}
}
public class ChildClass extends ParentClass( public static void main (String[] args){ ChildClass cc=new ChildClass();
long x=cc. doStuff(7);
System, out. println( "x="+x);
}
public long doStuff(int x) (
return x*3;
Public static void main (String[] args) {
X. x=new X ();
X. x2=ml (x);
X. x4=new X ();
X2=x4;
//comment
}
Static X ml(X mx)(
Mx=new X();
Return mx;
}
}
以上代码执行到comment处时有多少个可被垃圾收集的对象
给出以下代码
Public class TestObj{
Public static void main(String[] args){
Object o=new Object () {
Public boolean equals(Object obj){
Return true;
}
}；
System, out. printin(o. equals( "Fred"));
}
}
请给出结果：()
A运行时抛出异常
B True
C Fred
D第三行编译错误

Class Two(
Byte x;
Class PassO{
Public static void main(String[] args)( PassO p=new PassO();
P. start ();
}
Void start () {
Two t=new Two ();
System, out. print (t. x+” ” );
Two t2=fix(t);
System, out. print (t. x+” ” +t2・ x);
}
Two fix(Two tt)( tt. x=42;
Return tt;
}
}
请给出结果：
A null null 42 C 0 42 42 E Com