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多态与异常处理课后作业

时间:2015-11-15 16:24:17      阅读:126      评论:0      收藏:0      [点我收藏+]

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动手动脑:多层的异常捕获-1

源代码:

public class CatchWho {
public static void main(String[] args) {
try {
try {
throw new ArrayIndexOutOfBoundsException();
}
catch(ArrayIndexOutOfBoundsException e) {
System.out.println( "ArrayIndexOutOfBoundsException" + "/内层try-catch");
}

throw new ArithmeticException();
}
catch(ArithmeticException e) {
System.out.println("发生ArithmeticException");
}
catch(ArrayIndexOutOfBoundsException e) {
System.out.println( "ArrayIndexOutOfBoundsException" + "/外层try-catch");
}
}
}

运行结果:

技术分享

动手动脑:多层的异常捕获-2

源代码:

public class CatchWho2 {
public static void main(String[] args) {
try {
try {
throw new ArrayIndexOutOfBoundsException();
}
catch(ArithmeticException e) {
System.out.println( "ArrayIndexOutOfBoundsException" + "/内层try-catch");
}
throw new ArithmeticException();
}
catch(ArithmeticException e) {
System.out.println("发生ArithmeticException");
}
catch(ArrayIndexOutOfBoundsException e) {
System.out.println( "ArrayIndexOutOfBoundsException" + "/外层try-catch");
}
}
}

运行结果:

技术分享

动手动脑

当有多个嵌套的try…catch…finally时,要特别注意finally的执行时机。请先阅读示例,再运行它,观察其输出并进行总结。
源代码:


public class EmbededFinally {


public static void main(String args[]) {

int result;

try {

System.out.println("in Level 1");


try {

System.out.println("in Level 2");
// result=100/0; //Level 2

try {

System.out.println("in Level 3");

result=100/0; //Level 3

}

catch (Exception e) {

System.out.println("Level 3:" + e.getClass().toString());

}


finally {

System.out.println("In Level 3 finally");

}


// result=100/0; //Level 2


}

catch (Exception e) {

System.out.println("Level 2:" + e.getClass().toString());

}
finally {

System.out.println("In Level 2 finally");

}

// result = 100 / 0; //level 1

}

catch (Exception e) {

System.out.println("Level 1:" + e.getClass().toString());

}

finally {

. System.out.println("In Level 1 finally");

}

}

}

运行结果:
技术分享
结论:
当有多层嵌套的finally时,异常在不同的层次抛出 ,在不同的位置抛出,可能会导致不同的finally语句块执行顺序。
动手动脑:
辨析:finally语句块一定会执行吗?


public class SystemExitAndFinally {

public static void main(String[] args)
{
try{

System.out.println("in main");
throw new Exception("Exception is thrown in main");
//System.exit(0);

}
catch(Exception e)
{
System.out.println(e.getMessage());
System.exit(0);
}
finally
{
System.out.println("in finally");
}
}

}

运行结果:
技术分享
结论:finally语句不一定执行。

多态与异常处理课后作业

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原文地址:http://www.cnblogs.com/hyluckydog/p/4966708.html

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