java异常问题

[lv6917527]

1///
package sim;

public class NeedCleanup {
private static long counter=1;
private final long id = counter++;
public void dispose(){
System.out.println("NeedsCleanup"+id+"dispised");
}
}
class ConstructionException extends Exception{}

class NeedCleanup2 extends NeedCleanup{
public NeedCleanup2() throws ConstructionException{}
}


2///
package sim;

public class CleanIdiom {
public static void main(String[] args) {
NeedCleanup nc1 = new NeedCleanup();
try{

}finally{
nc1.dispose();
}
NeedCleanup nc2 = new NeedCleanup();
NeedCleanup nc3 = new NeedCleanup();
try{

}finally{
nc3.dispose();
nc2.dispose();
}
try{
NeedCleanup2 nc4 = new NeedCleanup2();
try{
NeedCleanup2 nc5 = new NeedCleanup2();
try{

}finally{
nc5.dispose();
}
}catch(ConstructionException e){
System.out.println(e);
}finally{
nc4.dispose();
}
}catch(ConstructionException e){
System.out.println(e);
}
}

}



看不懂这个，跑单步也看不懂，求网友们解释一下，谢谢了。

[天上掉个大馅饼]

了解一下finally子句，给你用颜色标注了一下

		try {
			...
		} finally {
			...
		}
		
		
		try {
			...
		} catch (Exception e) {
			...
		}
		
		try {
			...
		} catch (Exception e) {
                    ...
		} finally {
			...
		}
		
		try {
			...
			try {
				...
			} finally {
				...
			}
		} catch (Exception e) {
			...
		}

public class CleanIdiom { public static void main(String[] args) { NeedCleanup nc1 = new NeedCleanup(); try { } finally { nc1.dispose(); } NeedCleanup nc2 = new NeedCleanup(); NeedCleanup nc3 = new NeedCleanup(); try { } finally { nc3.dispose(); nc2.dispose(); } try { NeedCleanup2 nc4 = new NeedCleanup2(); try { NeedCleanup2 nc5 = new NeedCleanup2(); try { } finally { nc5.dispose(); } } catch (ConstructionException e) { System.out.println(e); } finally { nc4.dispose(); } } catch (ConstructionException e) { System.out.println(e); } } }

[lv6917527]

引用 1 楼 lonrence 的回复:

了解一下finally子句，给你用颜色标注了一下

		try {
			...
		} finally {
			...
		}
		
		
		try {
			...
		} catch (Exception e) {
			...
		}
		
		try {
			...
		} catch (Exception e) {
                    ...
		} finally {
			...
		}
		
		try {
			...
			try {
				...
			} finally {
				...
			}
		} catch (Exception e) {
			...
		}

public class CleanIdiom { public static void main(String[] args) { NeedCleanup nc1 = new NeedCleanup(); try { } finally { nc1.dispose(); } NeedCleanup nc2 = new NeedCleanup(); NeedCleanup nc3 = new NeedCleanup(); try { } finally { nc3.dispose(); nc2.dispose(); } try { NeedCleanup2 nc4 = new NeedCleanup2(); try { NeedCleanup2 nc5 = new NeedCleanup2(); try { } finally { nc5.dispose(); } } catch (ConstructionException e) { System.out.println(e); } finally { nc4.dispose(); } } catch (ConstructionException e) { System.out.println(e); } } }

引用 楼主 lv6917527 的回复:

1/// package sim; public class NeedCleanup { private static long counter=1; private final long id = counter++; public void dispose(){ System.out.println("NeedsCleanup"+id+"dispised"); } } class ConstructionException extends Exception{} class NeedCleanup2 extends NeedCleanup{ public NeedCleanup2() throws ConstructionException{} } 2/// package sim; public class CleanIdiom { public static void main(String[] args) { NeedCleanup nc1 = new NeedCleanup(); try{ }finally{ nc1.dispose(); } NeedCleanup nc2 = new NeedCleanup(); NeedCleanup nc3 = new NeedCleanup(); try{ }finally{ nc3.dispose(); nc2.dispose(); } try{ NeedCleanup2 nc4 = new NeedCleanup2(); try{ NeedCleanup2 nc5 = new NeedCleanup2(); try{ }finally{ nc5.dispose(); } }catch(ConstructionException e){ System.out.println(e); }finally{ nc4.dispose(); } }catch(ConstructionException e){ System.out.println(e); } } } 看不懂这个，跑单步也看不懂，求网友们解释一下，谢谢了。

引用 楼主 lv6917527 的回复:

1/// package sim; public class NeedCleanup { private static long counter=1; private final long id = counter++; public void dispose(){ System.out.println("NeedsCleanup"+id+"dispised"); } } class ConstructionException extends Exception{} class NeedCleanup2 extends NeedCleanup{ public NeedCleanup2() throws ConstructionException{} } 2/// package sim; public class CleanIdiom { public static void main(String[] args) { NeedCleanup nc1 = new NeedCleanup(); try{ }finally{ nc1.dispose(); } NeedCleanup nc2 = new NeedCleanup(); NeedCleanup nc3 = new NeedCleanup(); try{ }finally{ nc3.dispose(); nc2.dispose(); } try{ NeedCleanup2 nc4 = new NeedCleanup2(); try{ NeedCleanup2 nc5 = new NeedCleanup2(); try{ }finally{ nc5.dispose(); } }catch(ConstructionException e){ System.out.println(e); }finally{ nc4.dispose(); } }catch(ConstructionException e){ System.out.println(e); } } } 看不懂这个，跑单步也看不懂，求网友们解释一下，谢谢了。

嗯，就是不知道为什么打印的是 1 3 2 5 4 不是按顺序++的吗，在我看来，应该是12345 才对啊

[天上掉个大馅饼]

main方法里不是 顺序执行吗 构造的时候是1 2 3 4 5，调用方法的时候是1 3 2 5 4