题目内容
考虑如下代码：
class Tree{}
class Pine extends Tree{}
class Oak extends Tree{}
public class Forest {
public static void main(String[] args ) {
Tree tree = new Pine();
if(tree instanceof Pine )
System.out.println("Pine" );
if(tree instanceof Tree )
System.out.println("Tree" );
if(tree instanceof Oak )
System.out.println("Oak" );
else
System.out.println("Oops" );
}
}
则输出结果中有哪些？
查看答案
搜索结果不匹配？点我反馈
更多问题
编译和运行以下程序结果为：
1: public class Q21 {
2: int maxElements;
3: void Q21() {
4: maxElements = 100;
5: System.out.println(maxElements);
6: }
7: Q21(int i) {
8: maxElements = i;
9: System.out.println(maxElements);
10: }
11: public static void main(String[] args) {
12: Q21 a = new Q21();
13: Q21 b = new Q21(999);
14: }
15: }
下列说法错误的一项是？
下列程序运行的结果为：
public class Example{
String str=new String("good");
char[] ch={'a','b','c'};
public static void main(String args[]){
Example ex=new Example();
ex.change(ex.str,ex.ch);
System.out.print(ex.str+" and ");
Sytem.out.print(ex.ch);
}
public void change(String str,char ch[]){
str="test ok";
ch[0]='g';
}
}
以下程序调试结果为：class Base{Base（){int i = 100;System.out.print （i);}}public class Pri extends Base{static int i = 200;public static void main（String argv[]){Pri p = new Pri（);System.out.print（i);}}
微信支付 
支付宝支付