Исключения. Классы исключений

Август 3, 2022

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Исключения. Классы исключений

Содержание

2. VI. Исключения 2. Классы исключений
4. Класс Throwable public class Throwable implements Serializable { private String detailMessage; public Throwable() { fillInStackTrace(); }
5. Получение информации об исключении public class ExceptionMethodsDemo { public static void main(String[] args) { try {
6. Стек вызовов
8. Класс Throwable public class Throwable implements Serializable { private StackTraceElement[] stackTrace; public void printStackTrace() { printStackTrace(System.err);
9. Стек вызовов public class StackTraceDemo { static void methodA() throws Exception { throw new Exception(); }
10. Стек вызовов public class StackTraceDemo { ... public static void main(String[] args) { try { methodA();
11. Стек вызовов methodA main -------------------------------- methodA methodB main -------------------------------- methodA methodB methodC main
12. Стек вызовов public class AnotherStackTraceDemo { ... public static void main(String[] args) { try { methodA();
13. Стек вызовов java.lang.Exception at classes.AnotherStackTraceDemo.methodA(AnotherStackTraceDemo.java:6) at classes.AnotherStackTraceDemo.main(AnotherStackTraceDemo.java:19) -------------------------------- java.lang.Exception at classes.AnotherStackTraceDemo.methodA(AnotherStackTraceDemo.java:6) at classes.AnotherStackTraceDemo.methodB(AnotherStackTraceDemo.java:10) at classes.AnotherStackTraceDemo.main(AnotherStackTraceDemo.java:26) --------------------------------
14. Элемент стека вызовов
15. Класс Throwable public class Throwable implements Serializable { public void setStackTrace(StackTraceElement[] stackTrace) { StackTraceElement[] defensiveCopy =
16. Класс StackTraceElement public class StackTraceElement implements java.io.Serializable { private String declaringClass; private String methodName; private String
17. Элемент стека вызовов public class StackTraceElementDemo { public static void main(String[] args) { try { methodA();
18. Перебрасывание исключений из блока catch
20. Перебрасывание исключений public class RethrowingDemo { public static void methodA() throws Exception { System.out.println("Originating the exception
21. Перебрасывание исключений public class RethrowingDemo { public static void main(String[] args) { try { methodB(); }
22. Перебрасывание исключений Originating the exception in methodA() Inside methodB java.lang.Exception: Thrown from methodA() at classes.RethrowingDemo.methodA(RethrowingDemo.java:7) at
23. Сцепленные исключения
25. Не сцепленные исключения public class NoChainedExceptionDemo { public static void methodA() throws Exception { System.out.println("Originating the
26. Не сцепленные исключения Originating the exception in methodA() Throwing new exception in methodB() Throwing new exception
27. final final final Класс Throwable public class Throwable implements Serializable { private Throwable cause = this;
28. final final final Класс Throwable public class Throwable implements Serializable { public void printStackTrace(PrintStream s) {
29. Сцепленные исключения public class ChainedExceptionDemo { public static void methodA() throws Exception { System.out.println("Originating the exception
30. Сцепленные исключения Originating the exception in methodA() Throwing new exception in methodB() Throwing new exception in
32. Скачать презентацию

Слайд 2

VI. Исключения
2. Классы исключений

Слайд 3

Слайд 4

Класс Throwable
public class Throwable implements Serializable {
private String detailMessage;
public Throwable()

{
fillInStackTrace();
}
public Throwable(String message) {
fillInStackTrace();
detailMessage = message;
}
public String getMessage() {
return detailMessage;
}
public String getLocalizedMessage() {
return getMessage();
}
public String toString() {
String s = getClass().getName();
String message = getLocalizedMessage();
return (message != null) ? (s + ": " + message) : s;
}
}

Слайд 5

Получение информации об исключении
public class ExceptionMethodsDemo {
public static void main(String[]

args) {
try {
throw new Exception("My Exception");
} catch (Exception e) {
System.out.println("Caught Exception");
System.out.println("getMessage():" + e.getMessage());
System.out.println("getLocalizedMessage():"
+ e.getLocalizedMessage());
System.out.println("toString():" + e);
}
}
}
Caught Exception
getMessage():My Exception
getLocalizedMessage():My Exception
toString():java.lang.Exception: My Exception

Слайд 6

Стек вызовов

Слайд 7

Слайд 8

Класс Throwable
public class Throwable implements Serializable {
private StackTraceElement[] stackTrace;
public

void printStackTrace() {
printStackTrace(System.err);
}
public void printStackTrace(PrintStream s) {
synchronized (s) {
s.println(this);
StackTraceElement[] trace = getOurStackTrace();
for (int i=0; i < trace.length; i++)
s.println("\tat " + trace[i]);
Throwable ourCause = getCause();
if (ourCause != null)
ourCause.printStackTraceAsCause(s, trace);
}
}
public StackTraceElement[] getStackTrace() {
return (StackTraceElement[]) getOurStackTrace().clone();
}
private synchronized StackTraceElement[] getOurStackTrace() {
if (stackTrace == null) {
int depth = getStackTraceDepth();
stackTrace = new StackTraceElement[depth];
for (int i=0; i < depth; i++)
stackTrace[i] = getStackTraceElement(i);
}
return stackTrace;
}
native int getStackTraceDepth();
}

Слайд 9

Стек вызовов
public class StackTraceDemo {
static void methodA() throws Exception {

throw new Exception();
}
static void methodB() throws Exception {
methodA();
}
static void methodC() throws Exception {
methodB();
}
...
}

Слайд 10

Стек вызовов
public class StackTraceDemo {
...
public static void main(String[] args)

{
try {
methodA();
} catch (Exception e) {
for (StackTraceElement ste : e.getStackTrace())
System.out.println(ste.getMethodName());
}
System.out.println("--------------------------------");
try {
methodB();
} catch (Exception e) {
for (StackTraceElement ste : e.getStackTrace())
System.out.println(ste.getMethodName());
}
System.out.println("--------------------------------");
try {
methodC();
} catch (Exception e) {
for (StackTraceElement ste : e.getStackTrace())
System.out.println(ste.getMethodName());
}
}
}

Слайд 11

Стек вызовов
methodA
main
--------------------------------
methodA
methodB
main
--------------------------------
methodA
methodB
methodC
main

Слайд 12

Стек вызовов
public class AnotherStackTraceDemo {
...
public static void main(String[] args)

{
try {
methodA();
} catch (Exception e) {
e.printStackTrace(System.out);
}
System.out.println("--------------------------------");
try {
methodB();
} catch (Exception e) {
e.printStackTrace(System.out);
}
System.out.println("--------------------------------");
try {
methodC();
} catch (Exception e) {
e.printStackTrace(System.out);
}
}
}

Слайд 13

Стек вызовов
java.lang.Exception
at classes.AnotherStackTraceDemo.methodA(AnotherStackTraceDemo.java:6)
at classes.AnotherStackTraceDemo.main(AnotherStackTraceDemo.java:19)
--------------------------------
java.lang.Exception
at classes.AnotherStackTraceDemo.methodA(AnotherStackTraceDemo.java:6)
at classes.AnotherStackTraceDemo.methodB(AnotherStackTraceDemo.java:10)
at classes.AnotherStackTraceDemo.main(AnotherStackTraceDemo.java:26)
--------------------------------
java.lang.Exception
at classes.AnotherStackTraceDemo.methodA(AnotherStackTraceDemo.java:6)
at classes.AnotherStackTraceDemo.methodB(AnotherStackTraceDemo.java:10)
at classes.AnotherStackTraceDemo.methodC(AnotherStackTraceDemo.java:14)
at classes.AnotherStackTraceDemo.main(AnotherStackTraceDemo.java:33)

Слайд 14

Элемент стека вызовов

Слайд 15

Класс Throwable
public class Throwable implements Serializable {
public void setStackTrace(StackTraceElement[] stackTrace)

{
StackTraceElement[] defensiveCopy =
(StackTraceElement[]) stackTrace.clone();
for (int i = 0; i < defensiveCopy.length; i++)
if (defensiveCopy[i] == null)
throw new NullPointerException("stackTrace[" + i + "]");
this.stackTrace = defensiveCopy;
}
}

Слайд 16

Класс StackTraceElement
public class StackTraceElement implements java.io.Serializable {
private String declaringClass;

private String methodName;
private String fileName;
private int lineNumber;
public boolean isNativeMethod() { return lineNumber == -2; }
public StackTraceElement(String declaringClass, String methodName, String fileName, int lineNumber) {
if (declaringClass == null)
throw new NullPointerException("Declaring class is null");
if (methodName == null)
throw new NullPointerException("Method name is null");
this.declaringClass = declaringClass;
this.methodName = methodName;
this.fileName = fileName;
this.lineNumber = lineNumber;
}
public String toString() {
return getClassName() + "." + methodName +
(isNativeMethod() ? "(Native Method)" :
(fileName != null && lineNumber >= 0 ?
"(" + fileName + ":" + lineNumber + ")" :
(fileName != null ? "("+fileName+")" : "(Unknown Source)")));
}
...
}

Слайд 17

Элемент стека вызовов
public class StackTraceElementDemo {
public static void main(String[] args)

{
try {
methodA();
} catch (Throwable e) {
e.printStackTrace();
}
}
public static void methodA() throws RuntimeException {
RuntimeException t = new RuntimeException("This is a new Exception...");
StackTraceElement[] trace = new StackTraceElement[] { new StackTraceElement(
"ClassName", "methodName", "fileName", 5) };
t.setStackTrace(trace);
throw t;
}
}
java.lang.RuntimeException: This is a new Exception...
at ClassName.methodName(fileName:5)

Слайд 18

Перебрасывание исключений из блока catch

Слайд 19

Слайд 20

Перебрасывание исключений
public class RethrowingDemo {
public static void methodA() throws Exception

{
System.out.println("Originating the exception in methodA()");
throw new Exception("Thrown from methodA()");
}
public static void methodB() throws Exception {
try {
methodA();
} catch (Exception e) {
System.out.println("Inside methodB");
e.printStackTrace(System.out);
throw e;
}
}
public static void methodC() throws Exception {
try {
methodA();
} catch (Exception e) {
System.out.println("Inside methodC");
e.printStackTrace(System.out);
throw (Exception) e.fillInStackTrace();
}
}
}

Слайд 21

Перебрасывание исключений
public class RethrowingDemo {
public static void main(String[] args) {
try

{
methodB();
} catch (Exception e) {
System.out.println("Caught in main");
e.printStackTrace(System.out);
}
System.out.println();
try {
methodC();
} catch (Exception e) {
System.out.println("Caught in main");
e.printStackTrace(System.out);
}
}
}

Слайд 22

Перебрасывание исключений
Originating the exception in methodA()
Inside methodB
java.lang.Exception: Thrown from methodA()
at classes.RethrowingDemo.methodA(RethrowingDemo.java:7)
at

classes.RethrowingDemo.methodB(RethrowingDemo.java:12)
at classes.RethrowingDemo.main(RethrowingDemo.java:32)
Caught in main
java.lang.Exception: Thrown from methodA()
at classes.RethrowingDemo.methodA(RethrowingDemo.java:7)
at classes.RethrowingDemo.methodB(RethrowingDemo.java:12)
at classes.RethrowingDemo.main(RethrowingDemo.java:32)
Originating the exception in methodA()
Inside methodC
java.lang.Exception: Thrown from methodA()
at classes.RethrowingDemo.methodA(RethrowingDemo.java:7)
at classes.RethrowingDemo.methodC(RethrowingDemo.java:22)
at classes.RethrowingDemo.main(RethrowingDemo.java:38)
Caught in main
java.lang.Exception: Thrown from methodA()
at classes.RethrowingDemo.methodC(RethrowingDemo.java:26)
at classes.RethrowingDemo.main(RethrowingDemo.java:38)

Слайд 23

Сцепленные исключения

Слайд 24

Слайд 25

Не сцепленные исключения
public class NoChainedExceptionDemo {
public static void methodA() throws

Exception {
System.out.println("Originating the exception in methodA()");
throw new Exception("Thrown from methodA()");
}
public static void methodB() throws Exception {
try {
methodA();
} catch (Exception e) {
System.out.println("Throwing new exception in methodB()");
throw new Exception("Thrown from methodB()");
}
}
public static void methodC() {
try {
methodB();
} catch (Exception e) {
System.out.println("Throwing new exception in methodC()");
throw new RuntimeException("Thrown from methodC()");
}
}
public static void main(String[] args) {
methodC();
}
}

Слайд 26

Не сцепленные исключения
Originating the exception in methodA()
Throwing new exception in methodB()
Throwing

new exception in methodC()
Exception in thread "main" java.lang.RuntimeException: Thrown from methodC()
at classes.NoChainedExceptionDemo.methodC(NoChainedExceptionDemo.java:27)
at classes.NoChainedExceptionDemo.main(NoChainedExceptionDemo.java:32)

Слайд 27

final
final
final
Класс Throwable
public class Throwable implements Serializable {
private Throwable cause =

this;
public Throwable getCause() {
return (cause==this ? null : cause);
}
public Throwable(String message, Throwable cause) {
fillInStackTrace();
detailMessage = message;
this.cause = cause;
}
public synchronized Throwable initCause(Throwable cause) {
if (this.cause != this)
throw new IllegalStateException("Can't overwrite cause");
if (cause == this)
throw new IllegalArgumentException("Self-causation not permitted");
this.cause = cause;
return this;
}
}

Throwable cause

this.cause = cause

Слайд 28

final
final
final
Класс Throwable
public class Throwable implements Serializable {
public void printStackTrace(PrintStream s)

{
synchronized (s) {
s.println(this);
StackTraceElement[] trace = getOurStackTrace();
for (int i=0; i < trace.length; i++)
s.println("\tat " + trace[i]);
Throwable ourCause = getCause();
if (ourCause != null)
ourCause.printStackTraceAsCause(s, trace);
}
}
private void printStackTraceAsCause(PrintStream s, StackTraceElement[] causedTrace) {
StackTraceElement[] trace = getOurStackTrace();
int m = trace.length-1, n = causedTrace.length-1;
while (m >= 0 && n >=0 && trace[m].equals(causedTrace[n])) {
m--; n--;
}
int framesInCommon = trace.length - 1 - m;
s.println("Caused by: " + this);
for (int i=0; i <= m; i++)
s.println("\tat " + trace[i]);
if (framesInCommon != 0)
s.println("\t... " + framesInCommon + " more");
Throwable ourCause = getCause();
if (ourCause != null)
ourCause.printStackTraceAsCause(s, trace);
}
public Throwable getCause() {
return (cause==this ? null : cause);
}
}

printStackTraceAsCause

Слайд 29

Сцепленные исключения
public class ChainedExceptionDemo {
public static void methodA() throws Exception

{
System.out.println("Originating the exception in methodA()");
throw new Exception("Thrown from methodA()");
}
public static void methodB() throws Exception {
try {
methodA();
} catch (Exception e) {
System.out.println("Throwing new exception in methodB()");
throw new Exception("Thrown from methodB()", e);
}
}
public static void methodC() {
try {
methodB();
} catch (Exception e) {
System.out.println("Throwing new exception in methodC()");
throw new RuntimeException("Thrown from methodC()", e);
}
}
public static void main(String[] args) {
methodC();
}
}

Слайд 30

Сцепленные исключения
Originating the exception in methodA()
Throwing new exception in methodB()
Throwing new

exception in methodC()
Exception in thread "main" java.lang.RuntimeException: Thrown from methodC()
at classes.ChainedExceptionDemo.methodC(ChainedExceptionDemo.java:27)
at classes.ChainedExceptionDemo.main(ChainedExceptionDemo.java:32)
Caused by: java.lang.Exception: Thrown from methodB()
at classes.ChainedExceptionDemo.methodB(ChainedExceptionDemo.java:18)
at classes.ChainedExceptionDemo.methodC(ChainedExceptionDemo.java:24)
... 1 more
Caused by: java.lang.Exception: Thrown from methodA()
at classes.ChainedExceptionDemo.methodA(ChainedExceptionDemo.java:10)
at classes.ChainedExceptionDemo.methodB(ChainedExceptionDemo.java:15)
... 2 more

Исключения. Классы исключений

Содержание

VI. Исключения2. Классы исключений

Класс Throwablepublic class Throwable implements Serializable { private String detailMessage;public Throwable()

Получение информации об исключенииpublic class ExceptionMethodsDemo { public static void main(String[]

Стек вызовов

Класс Throwablepublic class Throwable implements Serializable { private StackTraceElement[] stackTrace; public

Стек вызововpublic class StackTraceDemo { static void methodA() throws Exception {

Стек вызововpublic class StackTraceDemo { ... public static void main(String[] args)

Стек вызововmethodAmain--------------------------------methodAmethodBmain--------------------------------methodAmethodBmethodCmain

Стек вызововpublic class AnotherStackTraceDemo { ... public static void main(String[] args)

Элемент стека вызовов

Класс Throwablepublic class Throwable implements Serializable { public void setStackTrace(StackTraceElement[] stackTrace)

Класс StackTraceElementpublic class StackTraceElement implements java.io.Serializable { private String declaringClass;

Элемент стека вызововpublic class StackTraceElementDemo { public static void main(String[] args)

Перебрасывание исключений из блока catch

Перебрасывание исключенийpublic class RethrowingDemo { public static void methodA() throws Exception

Перебрасывание исключенийpublic class RethrowingDemo { public static void main(String[] args) {try

Перебрасывание исключенийOriginating the exception in methodA()Inside methodBjava.lang.Exception: Thrown from methodA()at classes.RethrowingDemo.methodA(RethrowingDemo.java:7)at