225 lines
7.4 KiB
Java
225 lines
7.4 KiB
Java
/*
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* Copyright (C) 2007 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.base;
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import static com.google.common.base.Preconditions.checkNotNull;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import javax.annotation.Nullable;
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import com.google.common.annotations.Beta;
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import net.lax1dude.eaglercraft.v1_8.EagRuntime;
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/**
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* Static utility methods pertaining to instances of {@link Throwable}.
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*
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* <p>
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* See the Guava User Guide entry on
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* <a href= "http://code.google.com/p/guava-libraries/wiki/ThrowablesExplained">
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* Throwables</a>.
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*
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* @author Kevin Bourrillion
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* @author Ben Yu
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* @since 1.0
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*/
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public final class Throwables {
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private Throwables() {
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}
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/**
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* Propagates {@code throwable} exactly as-is, if and only if it is an instance
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* of {@code declaredType}. Example usage:
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*
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* <pre>
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* try {
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* someMethodThatCouldThrowAnything();
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* } catch (IKnowWhatToDoWithThisException e) {
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* handle(e);
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* } catch (Throwable t) {
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* Throwables.propagateIfInstanceOf(t, IOException.class);
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* Throwables.propagateIfInstanceOf(t, SQLException.class);
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* throw Throwables.propagate(t);
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* }
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* </pre>
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*/
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public static <X extends Throwable> void propagateIfInstanceOf(@Nullable Throwable throwable, Class<X> declaredType)
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throws X {
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// Check for null is needed to avoid frequent JNI calls to isInstance().
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if (throwable != null && declaredType.isInstance(throwable)) {
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throw declaredType.cast(throwable);
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}
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}
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/**
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* Propagates {@code throwable} exactly as-is, if and only if it is an instance
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* of {@link RuntimeException} or {@link Error}. Example usage:
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*
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* <pre>
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* try {
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* someMethodThatCouldThrowAnything();
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* } catch (IKnowWhatToDoWithThisException e) {
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* handle(e);
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* } catch (Throwable t) {
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* Throwables.propagateIfPossible(t);
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* throw new RuntimeException("unexpected", t);
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* }
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* </pre>
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*/
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public static void propagateIfPossible(@Nullable Throwable throwable) {
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propagateIfInstanceOf(throwable, Error.class);
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propagateIfInstanceOf(throwable, RuntimeException.class);
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}
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/**
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* Propagates {@code throwable} exactly as-is, if and only if it is an instance
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* of {@link RuntimeException}, {@link Error}, or {@code declaredType}. Example
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* usage:
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*
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* <pre>
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* try {
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* someMethodThatCouldThrowAnything();
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* } catch (IKnowWhatToDoWithThisException e) {
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* handle(e);
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* } catch (Throwable t) {
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* Throwables.propagateIfPossible(t, OtherException.class);
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* throw new RuntimeException("unexpected", t);
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* }
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* </pre>
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*
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* @param throwable the Throwable to possibly propagate
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* @param declaredType the single checked exception type declared by the calling
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* method
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*/
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public static <X extends Throwable> void propagateIfPossible(@Nullable Throwable throwable, Class<X> declaredType)
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throws X {
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propagateIfInstanceOf(throwable, declaredType);
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propagateIfPossible(throwable);
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}
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/**
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* Propagates {@code throwable} exactly as-is, if and only if it is an instance
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* of {@link RuntimeException}, {@link Error}, {@code declaredType1}, or
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* {@code declaredType2}. In the unlikely case that you have three or more
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* declared checked exception types, you can handle them all by invoking these
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* methods repeatedly. See usage example in
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* {@link #propagateIfPossible(Throwable, Class)}.
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*
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* @param throwable the Throwable to possibly propagate
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* @param declaredType1 any checked exception type declared by the calling
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* method
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* @param declaredType2 any other checked exception type declared by the calling
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* method
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*/
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public static <X1 extends Throwable, X2 extends Throwable> void propagateIfPossible(@Nullable Throwable throwable,
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Class<X1> declaredType1, Class<X2> declaredType2) throws X1, X2 {
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checkNotNull(declaredType2);
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propagateIfInstanceOf(throwable, declaredType1);
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propagateIfPossible(throwable, declaredType2);
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}
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/**
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* Propagates {@code throwable} as-is if it is an instance of
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* {@link RuntimeException} or {@link Error}, or else as a last resort, wraps it
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* in a {@code RuntimeException} then propagates.
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* <p>
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* This method always throws an exception. The {@code RuntimeException} return
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* type is only for client code to make Java type system happy in case a return
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* value is required by the enclosing method. Example usage:
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*
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* <pre>
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* T doSomething() {
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* try {
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* return someMethodThatCouldThrowAnything();
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* } catch (IKnowWhatToDoWithThisException e) {
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* return handle(e);
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* } catch (Throwable t) {
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* throw Throwables.propagate(t);
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* }
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* }
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* </pre>
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*
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* @param throwable the Throwable to propagate
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* @return nothing will ever be returned; this return type is only for your
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* convenience, as illustrated in the example above
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*/
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public static RuntimeException propagate(Throwable throwable) {
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propagateIfPossible(checkNotNull(throwable));
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throw new RuntimeException(throwable);
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}
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/**
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* Returns the innermost cause of {@code throwable}. The first throwable in a
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* chain provides context from when the error or exception was initially
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* detected. Example usage:
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*
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* <pre>
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* assertEquals("Unable to assign a customer id", Throwables.getRootCause(e).getMessage());
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* </pre>
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*/
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public static Throwable getRootCause(Throwable throwable) {
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Throwable cause;
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while ((cause = throwable.getCause()) != null) {
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throwable = cause;
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}
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return throwable;
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}
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/**
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* Gets a {@code Throwable} cause chain as a list. The first entry in the list
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* will be {@code throwable} followed by its cause hierarchy. Note that this is
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* a snapshot of the cause chain and will not reflect any subsequent changes to
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* the cause chain.
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*
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* <p>
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* Here's an example of how it can be used to find specific types of exceptions
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* in the cause chain:
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*
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* <pre>
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* Iterables.filter(Throwables.getCausalChain(e), IOException.class));
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* </pre>
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*
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* @param throwable the non-null {@code Throwable} to extract causes from
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* @return an unmodifiable list containing the cause chain starting with
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* {@code throwable}
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*/
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@Beta // TODO(kevinb): decide best return type
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public static List<Throwable> getCausalChain(Throwable throwable) {
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checkNotNull(throwable);
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List<Throwable> causes = new ArrayList<Throwable>(4);
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while (throwable != null) {
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causes.add(throwable);
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throwable = throwable.getCause();
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}
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return Collections.unmodifiableList(causes);
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}
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/**
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* Returns a string containing the result of {@link Throwable#toString()
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* toString()}, followed by the full, recursive stack trace of
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* {@code throwable}. Note that you probably should not be parsing the resulting
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* string; if you need programmatic access to the stack frames, you can call
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* {@link Throwable#getStackTrace()}.
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*/
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public static String getStackTraceAsString(Throwable throwable) {
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return EagRuntime.getStackTrace(throwable);
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}
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}
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