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Guava - THROWABLES CLASS

Throwables class provides utility methods related to Throwable interface.

Class Declaration

Following is the declaration for com.google.common.base.Throwables class:

Class Methods

S.N.	Method & Description
1	static List<Throwable> getCausalChain(Throwable throwable) Gets a Throwable cause chain as a list.
2	static Throwable getRootCause(Throwable throwable) Returns the innermost cause of throwable.
3	static String getStackTraceAsString(Throwable throwable) Returns a string containing the result of toString(), followed by the full, recursive stack trace of throwable.
4	static RuntimeException propagate(Throwable throwable) Propagates throwable as-is if it is an instance of RuntimeException or Error, or else as a last resort, wraps it in a RuntimeException then propagates.
5	static <X extends Throwable> void propagateIfInstanceOf(Throwable throwable, Class<X> declaredType) Propagates throwable exactly as-is, if and only if it is an instance of declaredType.
6	static void propagateIfPossible(Throwable throwable) Propagates throwable exactly as-is, if and only if it is an instance of RuntimeException or Error.
7	static <X extends Throwable> void propagateIfPossible(Throwable throwable, Class<X> declaredType) Propagates throwable exactly as-is, if and only if it is an instance of RuntimeException, Error, or declaredType.?
8	static <X1 extends Throwable,X2 extends Throwable>void propagateIfPossible(Throwable throwable, Class<X1> declaredType1, Class<X2> declaredType2) Propagates throwable exactly as-is, if and only if it is an instance of RuntimeException, Error, declaredType1, or declaredType2.

Methods Inherited

This class inherits methods from the following class:

java.lang.Object

Example of Throwables Class

Create the following java program using any editor of your choice in say C:/> Guava.

GuavaTester.java

import java.io.IOException;
import com.google.common.base.Objects;
import com.google.common.base.Throwables;
public class GuavaTester {
public static void main(String args[]){
GuavaTester tester = new GuavaTester();
try {
tester.showcaseThrowables();
} catch (InvalidInputException e) {
//get the root cause
System.out.println(Throwables.getRootCause(e));
}catch (Exception e) {
//get the stack trace in string format
System.out.println(Throwables.getStackTraceAsString(e));
}
try {
tester.showcaseThrowables1();
}catch (Exception e) {
System.out.println(Throwables.getStackTraceAsString(e));
}
}
public void showcaseThrowables() throws InvalidInputException{
try {
sqrt(-3.0);
} catch (Throwable e) {
//check the type of exception and throw it
Throwables.propagateIfInstanceOf(e, InvalidInputException.class);
Throwables.propagate(e);
}
}
public void showcaseThrowables1(){
try {
int[] data = {1,2,3};
getValue(data, 4);
} catch (Throwable e) {
Throwables.propagateIfInstanceOf(e, IndexOutOfBoundsException.class);
Throwables.propagate(e);
}
}
public double sqrt(double input) throws InvalidInputException{
if(input < 0) throw new InvalidInputException();
return Math.sqrt(input);
}
public double getValue(int[] list, int index) throws IndexOutOfBoundsException {
return list[index];
}
public void dummyIO() throws IOException {
throw new IOException();
}
}
class InvalidInputException extends Exception {
}

Verify the Result

Compile the class using javac compiler as follows:

C:\Guava>javac GuavaTester.java

Now run the GuavaTester to see the result.

C:\Guava>java GuavaTester

See the result.

InvalidInputException
java.lang.ArrayIndexOutOfBoundsException: 4
at GuavaTester.getValue(GuavaTester.java:52)
at GuavaTester.showcaseThrowables1(GuavaTester.java:38)
at GuavaTester.main(GuavaTester.java:19)

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Guava - THROWABLES CLASS