/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core;

import org.springframework.lang.Nullable;

Handy class for wrapping checked Exceptions with a root cause. 
This class is abstract to force the programmer to extend the class. getMessage will include nested exception information; printStackTrace and other like methods will delegate to the wrapped exception, if any. 
The similarity between this class and the NestedRuntimeException class is unavoidable, as Java forces these two classes to have different superclasses (ah, the inflexibility of concrete inheritance!). 
Author:
Rod Johnson, Juergen Hoeller
See Also:
getMessage
Throwable.printStackTrace
NestedRuntimeException/**
 * Handy class for wrapping checked {@code Exceptions} with a root cause.
 *
 * <p>This class is {@code abstract} to force the programmer to extend
 * the class. {@code getMessage} will include nested exception
 * information; {@code printStackTrace} and other like methods will
 * delegate to the wrapped exception, if any.
 *
 * <p>The similarity between this class and the {@link NestedRuntimeException}
 * class is unavoidable, as Java forces these two classes to have different
 * superclasses (ah, the inflexibility of concrete inheritance!).
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @see #getMessage
 * @see #printStackTrace
 * @see NestedRuntimeException
 */
public abstract class NestedCheckedException extends Exception {

	
Use serialVersionUID from Spring 1.2 for interoperability. /** Use serialVersionUID from Spring 1.2 for interoperability. */
	private static final long serialVersionUID = 7100714597678207546L;

	static {
		// Eagerly load the NestedExceptionUtils class to avoid classloader deadlock
		// issues on OSGi when calling getMessage(). Reported by Don Brown; SPR-5607.
		NestedExceptionUtils.class.getName();
	}


	
Construct a NestedCheckedException with the specified detail message. 
Params:
msg – the detail message/**
	 * Construct a {@code NestedCheckedException} with the specified detail message.
	 * @param msg the detail message
	 */
	public NestedCheckedException(String msg) {
		super(msg);
	}

	
Construct a NestedCheckedException with the specified detail message and nested exception. 
Params:
msg – the detail message
cause – the nested exception/**
	 * Construct a {@code NestedCheckedException} with the specified detail message
	 * and nested exception.
	 * @param msg the detail message
	 * @param cause the nested exception
	 */
	public NestedCheckedException(@Nullable String msg, @Nullable Throwable cause) {
		super(msg, cause);
	}


	
Return the detail message, including the message from the nested exception
if there is one.
/**
	 * Return the detail message, including the message from the nested exception
	 * if there is one.
	 */
	@Override
	@Nullable
	public String getMessage() {
		return NestedExceptionUtils.buildMessage(super.getMessage(), getCause());
	}


	
Retrieve the innermost cause of this exception, if any.
Returns:
the innermost exception, or null if none/**
	 * Retrieve the innermost cause of this exception, if any.
	 * @return the innermost exception, or {@code null} if none
	 */
	@Nullable
	public Throwable getRootCause() {
		return NestedExceptionUtils.getRootCause(this);
	}

	
Retrieve the most specific cause of this exception, that is,
either the innermost cause (root cause) or this exception itself.
Differs from getRootCause() in that it falls back to the present exception if there is no root cause. 
Returns:
the most specific cause (never null)
Since:
2.0.3/**
	 * Retrieve the most specific cause of this exception, that is,
	 * either the innermost cause (root cause) or this exception itself.
	 * <p>Differs from {@link #getRootCause()} in that it falls back
	 * to the present exception if there is no root cause.
	 * @return the most specific cause (never {@code null})
	 * @since 2.0.3
	 */
	public Throwable getMostSpecificCause() {
		Throwable rootCause = getRootCause();
		return (rootCause != null ? rootCause : this);
	}

	
Check whether this exception contains an exception of the given type:
either it is of the given class itself or it contains a nested cause
of the given type.
Params:
exType – the exception type to look for
Returns:
whether there is a nested exception of the specified type/**
	 * Check whether this exception contains an exception of the given type:
	 * either it is of the given class itself or it contains a nested cause
	 * of the given type.
	 * @param exType the exception type to look for
	 * @return whether there is a nested exception of the specified type
	 */
	public boolean contains(@Nullable Class<?> exType) {
		if (exType == null) {
			return false;
		}
		if (exType.isInstance(this)) {
			return true;
		}
		Throwable cause = getCause();
		if (cause == this) {
			return false;
		}
		if (cause instanceof NestedCheckedException) {
			return ((NestedCheckedException) cause).contains(exType);
		}
		else {
			while (cause != null) {
				if (exType.isInstance(cause)) {
					return true;
				}
				if (cause.getCause() == cause) {
					break;
				}
				cause = cause.getCause();
			}
			return false;
		}
	}

}