protocols/imap/src/main/java/org/apache/james/imap/decode/DecodingException.java

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package org.apache.james.imap.decode;

import java.io.IOException;
import java.util.Objects;

import org.apache.james.imap.api.display.HumanReadableText;

/**
 * <p>
 * Indicates that decoding failured.
 * </p>
 * <p>
 * All decoding exception should be supplied with:
 * </p>
 * <ul>
 * <li>A finely grained descriptive string</li>
 * <li>A coursely grained key for i18n</li>
 * </ul>
 * <p>
 * The following keys are frequently used when decoding:
 * </p>
 * <ul>
 * <li>{@link HumanReadableText#ILLEGAL_ARGUMENTS}</li>
 * <li>{@link HumanReadableText#BAD_IO_ENCODING}</li>
 * </ul>
 */
public class DecodingException extends IOException {

    private static final long serialVersionUID = 8719349386686261422L;

    private final HumanReadableText key;

    private Throwable t;

    /**
     * Constructs a decoding exception
     * 
     * @param key
     *            coursely grained i18n, not null
     * @param s
     *            specific description suitable for logging, not null
     */
    public DecodingException(HumanReadableText key, String s) {
        super(s);
        this.key = key;
    }

    /**
     * Constructs a decoding exception.
     * 
     * @param key
     *            coursely grained i18n, not null
     * @param s
     *            specific description suitable for logging, not null
     * @param t
     *            cause, not null
     */
    public DecodingException(HumanReadableText key, String s, Throwable t) {
        super(s);
        this.key = key;
        this.t = t;
    }

    /**
     * Gets the message key.
     * 
     * @return the key, not null
     */
    public final HumanReadableText getKey() {
        // API specifies not null but best to default to generic message
        return Objects.requireNonNullElse(this.key, HumanReadableText.ILLEGAL_ARGUMENTS);
    }

    @Override
    public Throwable getCause() {
        return t;
    }

}