Java开发网 - 如何为我的异常类加上 "return type"?

Topic: 如何为我的异常类加上 "return type"?

1.如何为我的异常类加上 "return type"?

Posted by: chuxueaihaozhe
Posted on: 2005-07-10 23:01

public class NewPrimeFinder implements Runnable {
public long target;
public long prime;
public boolean finished = false;
private Thread runner;

NewPrimeFinder(long inTarget) throws NegativeNumberException {
if (inTarget < 0) {
NegativeNumberException nne = new NegativeNumberException(
"Negative numbers not allowed: " + inTarget);
throw nne;
}
target = inTarget;
if (runner == null) {
runner = new Thread(this);
runner.start();
}
}

public void run() {
long numPrimes = 0;
long candidate = 2;
while (numPrimes < target) {
if (isPrime(candidate)) {
numPrimes++;
prime = candidate;
}
candidate++;
}
finished = true;
}

boolean isPrime(long checkNumber) {
double root = Math.sqrt(checkNumber);
for (int i = 2; i <= root; i++) {
if (checkNumber % i == 0)
return false;
}
return true;
}
}

class NegativeNumberException extends Exception {
NegativeNumberException() {
super();
}
NegativeNumberException(String message) {
super(message);
}
}
================================
c:\>javac PrimeFinder.java
PrimeFinder.java: :invalid method declaration;return type required
NegativeNumberException()
^
PrimeFinder.java: :invalid method declaration;return type required
NegativeNumberException(String message)
^
2 errors
=================================
Why?How?Help me!Thanks!

2.Re:如何为我的异常类加上 "return type"? [Re: chuxueaihaozhe]	Copy to clipboard
Posted by: why Posted on: 2005-07-11 00:11 c:\>javac PrimeFinder.java rename your java file NewPrimeFinder.java and try again.

3.Re:如何为我的异常类加上 "return type"? [Re: chuxueaihaozhe]	Copy to clipboard
Posted by: chuxueaihaozhe Posted on: 2005-07-11 21:26 no. c:\>javac NewPrimeFinder.java NewPrimeFinder.java: :invalid method declaration;return type required NegativeNumberException() ^ NewPrimeFinder.java: :invalid method declaration;return type required NegativeNumberException(String message) ^ 2 errors

4.Re:如何为我的异常类加上 "return type"? [Re: chuxueaihaozhe]	Copy to clipboard
Posted by: heart5 Posted on: 2005-07-15 07:46 chuxueaihaozhe wrote: no. c:\>javac NewPrimeFinder.java NewPrimeFinder.java: :invalid method declaration;return type required NegativeNumberException() ^ NewPrimeFinder.java: :invalid method declaration;return type required NegativeNumberException(String message) ^ 2 errors NB401下调试通过！一切正常

5.Re:如何为我的异常类加上 "return type"? [Re: chuxueaihaozhe]	Copy to clipboard
Posted by: chuxueaihaozhe Posted on: 2005-07-15 21:13 我用的是Java1.4.2及Windows2000中的记事本,这有关系吗?可不可以介绍一下 NB401,我不懂,别见笑.谢谢!

6.Re:如何为我的异常类加上 "return type"? [Re: chuxueaihaozhe]

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Posted by: why
Posted on: 2005-07-15 23:16

This has nothing to do with NB401.
Likely that you've messed up your enviroment.

please run the following commands and copy-n-paste the contents in the Command Prompt window into your post:
> echo %JAVA_HOME%
> echo %PATH%
> echo %CLASSPATH%
> dir
> type NewPrimeFinder.java
> javac NewPrimeFinder.java

(to cut-n-paste, select the area to capture with the mouse and press ENTER or right-click...)

7.Re:如何为我的异常类加上 "return type"? [Re: chuxueaihaozhe]

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Posted by: chuxueaihaozhe
Posted on: 2005-07-17 23:24

C:\myclass> echo %JAVA_HOME%
%JAVA_HOME%

C:\myclass> echo %PATH%
C:\j2sdk1.4.2\bin;C:\WINNT\AcGe16.dll;C:\Program Files\Common Files\Autodesk Shared\;C:\Program Files\backburner 2\

C:\myclass> echo %CLASSPATH%
.;C:\j2sdk1.4.2\lib\dt.jar;C:\j2sdk1.4.2\lib\tools.jar;C:\j2sdk1.4.2\jre\lib\rt.jar;C:\j2sdk1.4.2\jre\lib\charsets.jar;C:\j2sdk1.4.2\jre\lib\jaws.jar;C:\j2sdk1.4.2\lib\msbase.jar;C:\j2sdk1.4.2\lib\mssqlserver.jar;C:\j2sdk1.4.2lib\msutil.jar;C:\j2sdk1.4.2\lib\classes12.jar

C:\myclass> dir
驱动器c中的卷是DISK1_VOL1
卷的序列号0672-82C6
C:\myclass的目录
05/01/2005 09:31p <DIR> .
05/01/2005 09:31p <DIR> ..
07/14/2005 05:22P 1,089 NewPrimeFinder.java
* * * *
34个文件 20,017字节
2个目录 ***可用字节

C:\myclass>type NewPrimeFinder.java
public class NewPrimeFinder implements Runnable {
public long target;
public long prime;
public boolean finished = false;
private Thread runner;

NewPrimeFinder(long inTarget) throws NegativeNumberException {
if (inTarget < 0) {
NegativeNumberException nne = new NegativeNumberException(
"Negative numbers not allowed: " + inTarget);
throw nne;
}
target = inTarget;
if (runner == null) {
runner = new Thread(this);
runner.start();
}
}

public void run() {
long numPrimes = 0;
long candidate = 2;
while (numPrimes < target) {
if (isPrime(candidate)) {
numPrimes++;
prime = candidate;
}
candidate++;
}
finished = true;
}

boolean isPrime(long checkNumber) {
double root = Math.sqrt(checkNumber);
for (int i = 2; i <= root; i++) {
if (checkNumber % i == 0)
return false;
}
return true;
}
}

class NegativeNumberException extends Exception {
NegativeNumberException() {
super();
}
NegativeNumberException(String message) {
super(message);
}
}

C:myclass> javac NewPrimeFinder.java
C:\>javac NewPrimeFinder.java
NewPrimeFinder.java:44:invalid method declaration;return type required
NegativeNumberException()
^
NewPrimeFinder.java:47:invalid method declaration;return type required
NegativeNumberException(String message)
^
2 errors