BAEL-1921 - added example code and unit test for GlobalExceptionHandler (#4646)
* added example code and unit test for GlobalExceptionHandler * Code for common exceptions
This commit is contained in:
Mrudav Shukla
mikr
parent
13ce413ed2
commit
f56bf16d11
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package com.baeldung.exceptions;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class Arithmetic {
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private static Logger LOGGER = LoggerFactory.getLogger(Arithmetic.class);
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public static void main(String[] args) {
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try {
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int result = 30 / 0; // Trying to divide by zero
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} catch (ArithmeticException e) {
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LOGGER.error("ArithmeticException caught!");
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}
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}
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}
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package com.baeldung.exceptions;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class ArrayIndexOutOfBounds {
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private static Logger LOGGER = LoggerFactory.getLogger(ArrayIndexOutOfBounds.class);
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public static void main(String[] args) {
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int[] nums = new int[] { 1, 2, 3 };
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try {
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int numFromNegativeIndex = nums[-1]; // Trying to access at negative index
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int numFromGreaterIndex = nums[4]; // Trying to access at greater index
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int numFromLengthIndex = nums[3]; // Trying to access at index equal to size of the array
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} catch (ArrayIndexOutOfBoundsException e) {
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LOGGER.error("ArrayIndexOutOfBoundsException caught");
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}
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}
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}
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package com.baeldung.exceptions;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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class Animal {
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}
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class Dog extends Animal {
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}
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class Lion extends Animal {
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}
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public class ClassCast {
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private static Logger LOGGER = LoggerFactory.getLogger(ClassCast.class);
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public static void main(String[] args) {
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try {
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Animal animalOne = new Dog(); // At runtime the instance is dog
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Dog bruno = (Dog) animalOne; // Downcasting
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Animal animalTwo = new Lion(); // At runtime the instance is animal
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Dog tommy = (Dog) animalTwo; // Downcasting
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} catch (ClassCastException e) {
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LOGGER.error("ClassCastException caught!");
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}
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}
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}
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package com.baeldung.exceptions;
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import java.io.BufferedReader;
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import java.io.File;
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import java.io.FileNotFoundException;
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import java.io.FileReader;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class FileNotFound {
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private static Logger LOGGER = LoggerFactory.getLogger(FileNotFound.class);
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public static void main(String[] args) {
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BufferedReader reader = null;
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try {
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reader = new BufferedReader(new FileReader(new File("/invalid/file/location")));
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} catch (FileNotFoundException e) {
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LOGGER.error("FileNotFoundException caught!");
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}
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}
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}
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package com.baeldung.exceptions;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class GlobalExceptionHandler {
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public static void main(String[] args) {
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Handler globalExceptionHandler = new Handler();
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Thread.setDefaultUncaughtExceptionHandler(globalExceptionHandler);
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new GlobalExceptionHandler().performArithmeticOperation(10, 0);
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}
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public int performArithmeticOperation(int num1, int num2) {
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return num1/num2;
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}
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}
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class Handler implements Thread.UncaughtExceptionHandler {
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private static Logger LOGGER = LoggerFactory.getLogger(Handler.class);
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public void uncaughtException(Thread t, Throwable e) {
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LOGGER.info("Unhandled exception caught!");
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}
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}
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package com.baeldung.exceptions;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class IllegalArgument {
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private static Logger LOGGER = LoggerFactory.getLogger(IllegalArgument.class);
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public static void main(String[] args) {
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try {
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Thread.sleep(-1000);
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} catch (InterruptedException e) {
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LOGGER.error("IllegalArgumentException caught!");
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}
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}
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}
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package com.baeldung.exceptions;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class IllegalState {
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private static Logger LOGGER = LoggerFactory.getLogger(IllegalState.class);
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public static void main(String[] args) {
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List<Integer> intList = new ArrayList<>();
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for (int i = 0; i < 10; i++) {
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intList.add(i);
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}
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Iterator<Integer> intListIterator = intList.iterator(); // Initialized with index at -1
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try {
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intListIterator.remove(); // IllegalStateException
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} catch (IllegalStateException e) {
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LOGGER.error("IllegalStateException caught!");
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}
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}
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}
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package com.baeldung.exceptions;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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class ChildThread extends Thread {
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private static Logger LOGGER = LoggerFactory.getLogger(ChildThread.class);
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public void run() {
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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LOGGER.error("InterruptedException caught!");
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}
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}
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}
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public class InterruptedExceptionExample {
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public static void main(String[] args) throws InterruptedException {
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ChildThread childThread = new ChildThread();
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childThread.start();
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childThread.interrupt();
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}
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}
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package com.baeldung.exceptions;
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import java.net.MalformedURLException;
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import java.net.URL;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class MalformedURL {
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private static Logger LOGGER = LoggerFactory.getLogger(MalformedURL.class);
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public static void main(String[] args) {
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URL baeldungURL = null;
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try {
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baeldungURL = new URL("malformedurl");
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} catch (MalformedURLException e) {
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LOGGER.error("MalformedURLException caught!");
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}
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}
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}
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package com.baeldung.exceptions;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class NullPointer {
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private static Logger LOGGER = LoggerFactory.getLogger(NullPointer.class);
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public static void main(String[] args) {
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Person personObj = null;
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try {
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String name = personObj.personName; // Accessing the field of a null object
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personObj.personName = "Jon Doe"; // Modifying the field of a null object
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} catch (NullPointerException e) {
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LOGGER.error("NullPointerException caught!");
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}
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}
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}
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class Person {
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public String personName;
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public String getPersonName() {
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return personName;
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}
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public void setPersonName(String personName) {
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this.personName = personName;
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}
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}
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package com.baeldung.exceptions;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class NumberFormat {
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private static Logger LOGGER = LoggerFactory.getLogger(NumberFormat.class);
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public static void main(String[] args) {
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String str1 = "100ABCD";
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try {
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int x = Integer.parseInt(str1); // Converting string with inappropriate format
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int y = Integer.valueOf(str1);
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} catch (NumberFormatException e) {
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LOGGER.error("NumberFormatException caught!");
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}
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}
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}
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package com.baeldung.exceptions;
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import java.text.DateFormat;
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import java.text.ParseException;
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import java.text.SimpleDateFormat;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class ParseExceptionExample {
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private static Logger LOGGER = LoggerFactory.getLogger(ParseExceptionExample.class);
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public static void main(String[] args) {
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DateFormat format = new SimpleDateFormat("MM, dd, yyyy");
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try {
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format.parse("01, , 2010");
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} catch (ParseException e) {
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LOGGER.error("ParseException caught!");
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}
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}
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}
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package com.baeldung.exceptions;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class StringIndexOutOfBounds {
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private static Logger LOGGER = LoggerFactory.getLogger(StringIndexOutOfBounds.class);
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public static void main(String[] args) {
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String str = "Hello World";
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try {
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char charAtNegativeIndex = str.charAt(-1); // Trying to access at negative index
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char charAtLengthIndex = str.charAt(11); // Trying to access at index equal to size of the string
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} catch (StringIndexOutOfBoundsException e) {
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LOGGER.error("StringIndexOutOfBoundsException caught");
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}
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}
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}
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package com.baeldung.exceptions;
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import org.junit.After;
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import org.junit.Before;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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import org.mockito.ArgumentCaptor;
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import org.mockito.Captor;
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import org.mockito.Mock;
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import org.mockito.junit.MockitoJUnitRunner;
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import org.slf4j.LoggerFactory;
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import ch.qos.logback.classic.Level;
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import ch.qos.logback.classic.Logger;
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import ch.qos.logback.classic.spi.ILoggingEvent;
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import ch.qos.logback.classic.spi.LoggingEvent;
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import ch.qos.logback.core.Appender;
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import static org.assertj.core.api.Assertions.assertThat;
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import static org.mockito.Mockito.verify;
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@RunWith(MockitoJUnitRunner.class)
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public class GlobalExceptionHandlerUnitTest {
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@Mock
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private Appender<ILoggingEvent> mockAppender;
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@Captor
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private ArgumentCaptor<LoggingEvent> captorLoggingEvent;
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@Before
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public void setup() {
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final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
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logger.addAppender(mockAppender);
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Handler globalExceptionHandler = new Handler();
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Thread.setDefaultUncaughtExceptionHandler(globalExceptionHandler);
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}
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@After
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public void teardown() {
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final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
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logger.detachAppender(mockAppender);
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}
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@Test
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public void whenArithmeticException_thenUseUncaughtExceptionHandler() throws InterruptedException {
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Thread globalExceptionHandlerThread = new Thread() {
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public void run() {
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GlobalExceptionHandler globalExceptionHandlerObj = new GlobalExceptionHandler();
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globalExceptionHandlerObj.performArithmeticOperation(99, 0);
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}
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};
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globalExceptionHandlerThread.start();
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globalExceptionHandlerThread.join();
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verify(mockAppender).doAppend(captorLoggingEvent.capture());
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LoggingEvent loggingEvent = captorLoggingEvent.getValue();
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assertThat(loggingEvent.getLevel()).isEqualTo(Level.INFO);
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assertThat(loggingEvent.getFormattedMessage()).isEqualTo("Unhandled exception caught!");
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}
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}
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