第十章例外處理 - dns2.asia.edu.twdns2.asia.edu.tw/~wzyang/slides/Java/Chen/SE7ch10.pdf ·...

Java

10.1

10.2

10.5 throws

10.3

10.6

10.7

10.4

10.8

10.9

3

(1)

(2)

(3)

(Run Time Error)

10.1

4

10.1

5

JDK 7.0Java

10.1

6

000

y/(100-x)xx1000

10.1

7

AA

10.1

8

JavaJava

500Java

10.1

9

(Error)

(Exception)

(Exception)(Error)Java

10.1

10

10-1010-1ch10_01.javamyJava\ch10\ch10_01.java

10.1

12345678910111213141516

/* :ch10_01.java : */

package myJava.ch10;import java.lang.*;import java.io.Console;

public class ch10_01 //{

public static void main(String args[]){

fraction obj= new fraction();obj.set_value();obj.print_value();

} }

11

10.1

17181920212223242526272829303132333435

class fraction{

public fraction(){ console=System.console(); }private Console console;private int numerator; //private int denominator; //public void set_value(){

System.out.print(":");numerator=Integer.parseInt(console.readLine()); System.out.print(":");denominator=Integer.parseInt(console.readLine());

}public void print_value(){

System.out.print(numerator + "/" + denominator + "=");System.out.println(numerator/denominator);

}}

12

(1)84Java

C:\>java myJava.ch10.ch10_01:8:4 8/4=2

C:\>java myJava.ch10.ch10_01:2:02/0=Exception in thread "main" java.lang.ArithmeticException: / by zero

at myJava.ch10.fraction.print_value(ch10_01.java:33)at myJava.ch10.ch10_01.main(ch10_01.java:13)

10.1

13

(2)203320

10-1if0

if-elseif-elseJava

10-1Java

2/0=Exception in thread

10.1

14

Java

Java

(1)Java

(2)

10.2

15

Javajava.lang.Throwable

java.lang.Exception

java.lang.Error

java.lang.ErrorJVMError

10.2.1 Java

16

java.lang.Exception

10-1java.lang.ArithmeticException0

NegativeArraySizeException

10.2.1 Java

17

Java

B-1B.8BufferedReaderreadLine(throw) IOException

readLinepublic String readLine() throws IOExceptionReads a line of text. A line is considered to be terminated by any one of a line feed ('\n'), a carriage return ('\r'), or a carriage return followed immediately by a linefeed. Returns:A String containing the contents of the line, not including any line-termination characters, or null if the end of the stream has been reached Throws: IOException - If an I/O error occurs

10.2.1 Java

18

IOExceptionIO

IOExceptionjava.lang.Exception

10.2.1 Java

19

java.lang.RuntimeException

10.2.1 Java

java.lang.Exception java.lang.ClassNotFoundException

java.lang.CloneNotSupportedException Objectclone()CloneableJavacloneCloneable

java.lang.IllegalAccessException

java.lang.InstantiationException newInstance()

java.lang.InterruptedException

java.lang.NoSuchFieldException

java.lang.NoSuchMethodException

java.lang.RuntimeException JVM

20

java.lang.RuntimeException java.lang.ArithmeticException 0java.lang.ArrayStoreException

java.lang.ClassCastException java.lang.EnumConstantNotPresentException java.lang.IllegalArgumentExceptionjava.lang.IllegalThreadStateExceptionjava.lang.NumberFormatException

java.lang.IllegalMonitorStateException java.lang.IllegalStateException

java.lang.IndexOutOfBoundsExceptionjava.lang.ArrayIndexOutOfBoundsExceptionjava.lang.StringIndexOutOfBoundsException

charAt

java.lang.NegativeArraySizeException 0java.lang.NullPointerException

nulljava.lang.SecurityException Java

java.lang.TypeNotPresentException java.lang.UnsupportedOperationException

10.2.1 Java

21

JavaJavaJava

Throwable

ExceptionThrowable

10.2.2

class extends Exception{

public () //{

super(); ////

}//

}

22

throw

Java

10-2

10-2ch10_02.javamyJava\ch10\ch10_02.java

10.3

23

1234567891011121314

/* :ch10_02.java : */

package myJava.ch10;import java.lang.*;



System.out.println("");int ary[] = new int[-2];System.out.println("");

} }

C:\>java myJava.ch10.ch10_02Exception in thread "main" java.lang.NegativeArraySizeException

at myJava.ch10.ch10_02.main(ch10_02.java:11)

10.3

24

11NegativeArraySizeException12

throwthrow

10.3

25

10-3throw10-3ch10_03.javamyJava\ch10\ch10_03.java

1234567891011121314151617

/* :ch10_03.java :throw */




System.out.println("");int i=-2;if(ijava myJava.ch10.ch10_03Exception in thread "main" java.lang.NegativeArraySizeException


10.3

27

10-4throw


1234567891011121314151617

/* :ch10_04.java :throw */



public static void main(String args[]) throws CmyException{

System.out.println("");int i=-2;if(ijava myJava.ch10.ch10_04Exception in thread "main" myJava.ch10.CmyException:


181920212223242526272829

class CmyException extends Exception{

public CmyException() //{

super();}public CmyException(String msg) //{

super(msg);}

}

10.3

29

(1)main()throws CmyException

(2)

(3)14~15

Coding

GUI

Coding

GUI

10.3

30

Javatrythrowcatchfinally

throw

trycatch[finally]

finally

10.4

31

trycatch[finally] try

{//

}catch(1 |2| ){

//}catch(3 | ){

//}.......catch............finally{

//}//

|

10.4

32

(1)trythrow(2)catchcatch(3)catchcatchcatch|orJDK7.0Multi-catchcatch(1 |2 )|

10.4

33

(4)finally

(5)trycatch[finally]trycatchJavacatchcatchJava

(6)catch

(7)trycatch[finally]

(8)10-1

10.4

34

10.4

10-1

35

10-56~486


12345678

/* :ch10_05.java :Multi-catch */



10.4

36

10.49101112131415161718192021222324252627282930313233343536


Console console=System.console();System.out.print(":");int lottoSize=0;

try{ lottoSize=Integer.parseInt(console.readLine()); if(lottoSize>48)

throw new CmyException1(":"); else if(lottoSize

37

10.4

3738394041424344454647484950515253545556575859606162

class CmyException1 extends Exception{

public CmyException1() //{

super();}public CmyException1(String msg) //{

super();System.out.println(msg);

} }



super();}public CmyException2(String msg) //{

super();System.out.println(msg);

} }

38

:99

:99::66

10.4

:r0Exception in thread "main" java.lang.NumberFormatException: For input string: "r"

at java.lang.NumberFormatException.forInputString(Unknown Source)at java.lang.Integer.parseInt(Unknown Source)at java.lang.Integer.parseInt(Unknown Source)at myJava.ch10.ch10_05.main(ch10_05.java:17)

:5::66

39

(1)6~48

(2)38~626~48

(3)15~31trycatch[finally]1718~21lottoSizetrythrowthrow

(4)catchtryfinallytrycatch[finally]

10.4

40

(5)184819throw23~27catchfinallytrycatch[finally](6)20621throw23~27catchfinallytrycatch[finally](7)17throwcatchfinally0(8)10-7

10.4

41

(9)23~27Multi-catchcatchCmyException1CmyException2JDK6

10.4

2324252627:::::

catch(CmyException1 e){ System.out.println(":6");lottoSize=6;

}catch(CmyException2 e){ System.out.println(":6");lottoSize=6;

}

42

10.4

10110523~27(9)

10110523~27(9)

10210551classCmyException2extendsCmyException1

10210551classCmyException2extendsCmyException1

43

Multi-catchMulti-catchcatch(|)

10-2CmyException2CmyException1catch(|)

10.4

44

10-6Multi-catch


10.4

1234567

/* :ch10_06.java : Multi-catch */



45

10.4

89101112131415161718192021222324252627282930313233


int lottoSize=99;

try{ if(lottoSize>48)

throw new CmyException1(); else if(lottoSize

47

10.4

52535455565758596061626364656667



super();}public void showMessage(){

System.out.println(":");}public int changeSize(){

System.out.println(":6");return 6;

}}

48

10.4

C:\myJava\ch10>javac ch10_06.javach10_06.java:21: error: cannot find symbol

e.showMessage();^

symbol: method showMessage()location: variable e of type Exception

ch10_06.java:22: error: cannot find symbollottoSize=e.changeSize();

^symbol: method changeSize()location: variable e of type Exception

2 errors

49

(1)Multi-catchcatchmethod2122showMessage()changeSize()CmyException1CmyException2methods

(2)19~23Multi-catch

10.4

1920212223::::::

catch(CmyException1 e){

e.showMessage();lottoSize=e.changeSize();

} catch(CmyException2 e){e.showMessage();lottoSize=e.changeSize();

}

50

(3)JDK7bugemethod

CmyException1CmyException2JDK7

JDK7bugJDK7Multi-catchmethod

methodMulti-catchcatch

10.4

51

10.4

106JDK7MulticatchmethodJDKbugJDK7MulticatchJDK7method10621~22emethodshowMessage()changeSize()JDK7106JDK7bugJDK7106JDK7Multicatchmethod

106JDK7MulticatchmethodJDKbugJDK7MulticatchJDK7method10621~22emethodshowMessage()changeSize()JDK7106JDK7bugJDK7106JDK7Multicatchmethod

10310619~23(2)

10310619~23(2)

52

10-510-5catch

10-710-7ch10_07.javamyJava\ch10\ch10_07.java

10.4

12345678910111213

/* :ch10_07.java : */




Console console=System.console();System.out.print(":");int lottoSize=0;

53

14151617181920212223242526272829303132333435363738394041

try{

lottoSize=Integer.parseInt(console.readLine()); if(lottoSize>48)


55

10-5NumberFormatException23~27catchr

:r,66

10.4

56

try{

//}catch(1 | 2 | ){

//} catch(Exception ) {

//} finally{

//}

10.4

57

catchExceptioncatchExceptioncatch

10.4

Coding

trycatchcatchcatchcatchcatchJDK7Multicatchcatch(|)

Coding

trycatchcatchcatchcatchcatchJDK7Multicatchcatch(|)

58

10-8


10.4

1234567891011121314

/* :ch10_08.java : */




Console console=System.console(); int lottoSize=0;int lottoAry[];

59

10.4

151617181920212223242526272829303132333435363738

while(true){

try{ System.out.print(":");lottoSize=Integer.parseInt(console.readLine()); lottoAry = new int[lottoSize]; break; //while

}catch(NumberFormatException e){System.out.println("");

} catch(Exception e){System.out.println("");

} finally{}

}System.out.println("...");

} }

60

(1)28~31catchExceptioncatchcatchr24~27catch-228~31catch(2)trycatchtrybreakcatchbreak

10.4:r:-2:3...

61

(1)30~33catchExceptioncatchcatchr26~29catch-230~33catch

(2)trycatchtrybreakcatchbreak

10.4

62

trycatchtrycatch(method)try

10.5 throws

63

throws

(1),(2)trycatch

[] [] () throws 1,2,{

//}

10.5 throws

64

(3)RuntimeException

10.5 throws

10-2

65

10-9


10.5 throws

123456789101112

/* :ch10_09.java : */




CmyClass obj = new CmyClass();

66

1314151617181920212223242526272829303132333435

try{

obj.setValue(); //obj.printValue(); //

}catch(NumberFormatException e){

System.out.println(":");}catch(ArithmeticException e){

System.out.println(":0");} catch(Exception e){

System.out.println("");} finally{}

} }

10.5 throwstry

67

10.5 throws

3637383940414243444546474849505152535455

class CmyClass{

private int numerator,denominator; public Console console=System.console();

public void setValue() throws NumberFormatException{

System.out.print(":");numerator=Integer.parseInt(console.readLine()); System.out.print(":");denominator=Integer.parseInt(console.readLine()); System.out.println("");

}

public void printValue() throws ArithmeticException{

System.out.println("" + numerator/denominator);System.out.println("");

}}

68

(1)try15~16catch(2)41~54throws(3)NumberFormatExceptionArithmeticExceptionRuntimeException

:5:t:

:5:0:0

10.5 throws

69

RuntimeExceptionRuntimeExceptionRuntimeExceptionJVM

throwscatch

10.5 throws

70

10-9catchcatch

RuntimeException

10.5 throws

71

throwsthrowsthrowthrowsRuntimeException

JDKJavatrycatch

10.5 throws

72

throws10-1010-10ch10_10.javamyJava\ch10\ch10_10.java

10.6

1234567891011

/* :ch10_10.java : */




CmyClass2 obj2 = new CmyClass2();

73

1213141516171819202122232425262728293031323334

try{

obj2.run(); //}catch(NumberFormatException e){

System.out.println(":");}catch(ArithmeticException e){

System.out.println(":0");} catch(Exception e){

System.out.println("");} finally{}

} }

10.6

74

10.6 353637383940414243444546474849505152535455565758596061626364

class CmyClass1{

private int numerator,denominator; public Console console=System.console();

public void setValue() throws NumberFormatException{

System.out.print(":");numerator=Integer.parseInt(console.readLine()); System.out.print(":");denominator=Integer.parseInt(console.readLine()); System.out.println("");

}

public void printValue() throws ArithmeticException{

System.out.println("" + numerator/denominator);System.out.println("");

}}

class CmyClass2{

public CmyClass1 obj1 = new CmyClass1();public void run() throws NumberFormatException,ArithmeticException{

obj1.setValue(); //obj1.printValue(); //.

}}

run()run()(15)

75

10-9

(1)CmyClass1CmyClass2runrunrun15

(2)59RuntimeExceptionB-1B.8mainthrows IOException

10.6

76

readLineIOExceptionB-1B-1

B-1mainthrows IOExceptionreadLinemainmainIOExceptionRuntimeExceptionmainJVMJVM

10.6

77

mainmainthrows IOException

10-11B-1mainIOException10-11ch10_11.javamyJava\ch10\ch10_11.java

10.6

123456

/* :ch10_11.java :mainIOException */

package myJava.ch10;import java.lang.*;import java.io.*;

78

789101112131415161718192021222324252627282930


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

try{

BufferedReader buf;String str1,str2;

System.out.print(":");buf = new BufferedReader(new InputStreamReader(System.in));str1 = buf.readLine();System.out.print(":");str2 = buf.readLine();System.out.println(":");System.out.println(str1);System.out.println(str2);

}catch(IOException e){

//,}

}}

10.6

79

B-1

tryIOException

readLine

27

10.6

80

trycatch[finally]trycatch[finally]

trycatchfinallytry

10.7

81

10-12


12345678910111213

/* :ch10_12.java : */




Console console=System.console(); int ary[]=new int[]{0,5,10,15,20,25,30,35,40,45};int x=0,num=0;

10.7

82

10.7

1415161718192021222324252627282930313233343536

try //try{

System.out.print(":");x=Integer.parseInt(console.readLine());

try{num=ary[x];System.out.println("ary[" + x + "]=" + num);

}catch(ArrayIndexOutOfBoundsException e){System.out.println(":!");

} }catch(NumberFormatException e) //catch{

System.out.println(":!");}

System.out.println("......"); }

}

83

(1)14~32trycatch19~27trytrycatch

(2)16,17,21,22172116~17trycatchtrycatch21,22

:r:!......

:15:!......

10.7

84

(3)trycatch

(4)trycatch16,17,21,22try

(5)16,17trycatchcatch

10.7

85

throw

5catchcatch

catchcatchcatch

10.8

86

10-13


12345678910111213

/* :ch10_13.java : */




Console console=System.console(); int ary[]=new int[]{0,5,10,15,20,25,30,35,40,45};int x=0,num=0;

10.8

87

10.814151617181920212223242526272829303132333435363738394041

try //try{

try{

System.out.print(":");x=Integer.parseInt(console.readLine());num=ary[x];System.out.println("ary[" + x + "]=" + num);

}catch(ArrayIndexOutOfBoundsException e){

System.out.println(":!");} catch(NumberFormatException e){

System.out.println(",");throw e;

}

}catch(NumberFormatException e) //catch{

System.out.println(":!");}

System.out.println("......"); }

}

34NumberFormatException

88

283034catch34catchcatch

:r,:!......

10.8

104101330104101330

89

(Precise rethrow with a final Exception)

JDK7Precise rethrow with a final Exception

methodtry-catchcatchcatch(Exception e)

methodcatch(Exception e)throws Exception

10.8

90

10.8

publicvoidtest()throwsException{try{//1,2

}catch(1e){

//}catch(2e){

//}catch(Exceptione){throwe;//

}}

91

test()test()

test()test()test()

10.8

publicvoidcaller(){try{Obj1.test();//1,2

}catch(Exceptione){//test()

}}

92

java.io.BufferedInputStreamread()

public int read() throws IOException

IOExceptionthrows Exception

10.8

93

test()

test()3434

test()

10.8

publicvoidtest()throws3,4,Exception{

test()}

94

10.8

publicvoidcaller(){try{Obj1.test();//1,2

}catch(3e){//test()3

}catch(4e){//test()4

}catch(Exceptione){//test()34

}}

95

JDK6JDK7

JDK7test()

JDK7test()throw eePrecise rethrow with a final Exception

10.8

publicvoidtest()throws3,4 //JDK7{

test()}

96

Precise rethrow with a final ExceptionJDK6JDK7

10.8

97

10-14


10.8

12345678910111213141516171819

/* :ch10_14.java :Precise rethrow with a final Exception */



public static void main(String args[]) {

Console console=System.console();System.out.print(":");int lottoSize=0;CmyClass1 obj1=new CmyClass1();

try{ lottoSize=obj1.check(console.readLine()); //

}

98

10.820212223242526272829303132333435363738394041424344454647

catch(CmyException1 e){

System.out.println(":6");lottoSize=6;

}catch(CmyException2 e){

System.out.println(":6");lottoSize=6;

} catch(NumberFormatException e){

System.out.println(",6");lottoSize=6;

} catch(Exception e){

System.out.println(":");} finally{

System.out.println("" + lottoSize);}

int lottoAry[] = new int[lottoSize];System.out.println("");

} }

99

10.8

4849505152

5354555657585960616263646566676869

class CmyClass1{

private int lottoSize; public void check(String inputStr)

throws CmyException1,CmyException2,NumberFormatException{try {

lottoSize=Integer.parseInt(inputStr); if(lottoSize>48)


101

JDK6

JDK7

10.8

C:\myJava\ch10>javac ch10_14.javach10_14.java:67: unreported exception java.lang.Exception; must be caught or declared to be thrown

throw e;^

1 error

:5::66

:r,66

102

(1)18check()52check()CmyException1, CmyException2, NumberFormatExceptionException20~38

(2)CmyClass1check()63~66

NumberFormatException52

10.8

103

throws CmyException1, CmyException2, NumberFormatException, ExceptionJDK7, ExceptionJDK6, Exception63~66

(3)63finalfinal

10.8

trywithresourcesJDK7trycatchmulticatchPreciserethrowwithafinalException

trywithresourcesJDK7trycatchmulticatchPreciserethrowwithafinalException

104

(Error)

(Exception)

(Exception)

10.9

105

(1)Java

(2)(1)Java(2)

(3)java.lang.Exceptionjava.lang.ArithmeticException

(4)ThrowableException

(5)throw

10.9

106

(6)Javatrythrowcatchfinally(7)trycatch[finally]finally(8)trycatchcatch(9)catch(Exception )catch(10)throws throwsRuntimeException

10.9

107

(11)trycatch[finally]trycatch[finally]try

(12)JDK7try-catchcatchmulti-catchcatch(final Exception e){ throw e; }ExceptionthrowsPrecise rethrow with a final Exception

10.9

108

Q&A

第十章例外處理 - dns2.asia.edu.twdns2.asia.edu.tw/~wzyang/slides/Java/Chen/SE7ch10.pdf ·...

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