Carnegie Mellon University

Java Programming Course

Java Programming

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Java Programming Virtual Lecture 17

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Table of Contents

Java Programming Virtual Lecture 17

Recall System.java’s objects in and out

Recall System.java’s objects in and out

Recall global variables are available for use

InputStream.java

ReadByte.java reads a char from the keyboard

ReadByte.java reads a char from the keyboard

ReadByte.java reads a char from the keyboard

ReadByte.java reads a char from the keyboard

ReadByte.java reads a char from the keyboard

ReadByte.java reads a char from the keyboard

Special Characters

ReadByte.java reads a char from the keyboard, Step 15

ReadByte.java reads a char from the keyboard, Step 16

Recall Cast char to int and int to char

ReadByte.java reads a char from the keyboard, Step 19

System.in.read() Summary

Recall types of errors

Focus on execution errors

Handling execution errors

Exception handling

ReadByte.java reads a char from the keyboard

ReadByte.java reads a char from the keyboard

ReadByte.java reads a char from the keyboard

DivException1.java dividing by zero causes an error

DivException2.java example of a Java exception

DivException2.java example of try--catch

DivException3.java example of try—catch--finally

DivException4.java example of try—catch—finally with return

DivException5a.java example of try--finally

DivException5b.java example of a Java exception

Multiple catch clauses

Recall InputStream.java

Class Hierarchy for Exception

Recall Exception in catch

Using IOException

Class Hierarchy for IOException

Class Hierarchy, Object class

TestObject.java

Class Hierarchy, Throwable class

Throwable.java, Constructors

Throwable.java, toString()

TestThrowable.java

Throwable.java, getMessage()

TestGetMessage.java

Throwable.java, printStackTrace()

TestStackTrace.java

TestStackTrace.java

Recall TestStackTrace.java

TestStackTrace.java

Class Hierarchy, Exception class

Probable contents of Exception.java

TestException.java writing our own exception class

The throw command

TestThrowing.java throwing exceptions (throw)

ThrowStack.java

ThrowStack.java

Exception handler

ThrowStack.java

Ways to handle errors

Error-checking: the Square6 program

Error-signaling: the Square7a program

Recall ReadByte.java reads a character from the keyboard

Error-trapping: Modify ReadByte.java reads a digit from the keyboard

Ways to handle errors

Author: Latanya Sweeney

Email: latanya@andrew.cmu.edu

Home Page: http://lab.privacy.cs.cmu.edu/index.html