Question

一Java小程序出现异常

下面是我写的程序
class MyException2 extends Exception{

/**the second myexception
*/
MyException2(String s){
super(s);
System.out.println("that's my exception");
}
public class TestException{

public int add(int a,int b) throws MyException2{
int c=a+b;
if (c>999) throw new MyException2("c is too big");
else return c;
}
}
public static void main(String[] args) {

TestException test=new TestException();

try{

int[] i=new int[2];
test.add(i[0],i[1]);
}catch(MyException2 e){
e.printStackTrace();
}
}
}
在这一句TestException test=new TestException();出现了错误，提示说No enclosing instance of type MyException2 is accessible. Must qualify the allocation with an enclosing instance of type MyException2 (e.g. x.new A() where x is an instance of MyException2).

请帮忙看下，十分感谢。

Answer 1

把最后一个大括号移到System.out.println("that's my exception");
} 后，变为：
System.out.println("that's my exception");
}
}

缺少默认的构造函数，把
class MyException2 extends Exception{

/**the second myexception
*/
MyException2(String s){
super(s);
System.out.println("that's my exception");
}
}
改为：
class MyException2 extends Exception{

/**the second myexception
*/
MyException2(String s){
super(s);
System.out.println("that's my exception");
}
MyException2(){}
}

Answer 2

两个类文件分开写,
MyException2 .java

class MyException2 extends Exception{

/**the second myexception
*/
MyException2(String s){
super(s);
System.out.println("that's my exception");
public static void main(String[] args) {

TestException test=new TestException();

try{

int[] i=new int[2];
test.add(i[0],i[1]);
}catch(MyException2 e){
e.printStackTrace();
}
}
}

TestException.java

public class TestException{
public int add(int a,int b) throws MyException2{
int c=a+b;
if (c>999) throw new MyException2("c is too big");
else return c;
}
}

是没有任何异常信息。但不知道你要什么结果了

Answer 3

这样该就可以了
MyException2.java

class MyException2 extends Exception{

/**the second myexception
*/
MyException2(String s){
super(s);
System.out.println("that's my exception");
}

public static void main(String[] args) {

TestException test=new TestException();

try{

int[] i=new int[2];
test.add(999,2);
}catch(MyException2 e){
e.printStackTrace();
}
}
}
class TestException{

public int add(int a,int b) throws MyException2{
int c=a+b;
if (c>999) throw new MyException2("c is too big");
else return c;
}
}

Answer 4

else return c;
}
后面的大括号删除。

Answer 5

你{ }的范围有点问题