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package java.lang;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamField;

Thrown when an application tries to load in a class through its
string name using:

The forName method in class Class. 
The findSystemClass method in class ClassLoader . 
The loadClass method in class ClassLoader. 

but no definition for the class with the specified name could be found.
See Also:
Class.forName(String)
ClassLoader.findSystemClass(String)
ClassLoader.loadClass(String, boolean)
Since:
  1.0/**
 * Thrown when an application tries to load in a class through its
 * string name using:
 * <ul>
 * <li>The {@code forName} method in class {@code Class}.
 * <li>The {@code findSystemClass} method in class
 *     {@code ClassLoader} .
 * <li>The {@code loadClass} method in class {@code ClassLoader}.
 * </ul>
 * <p>
 * but no definition for the class with the specified name could be found.
 *
 * @see     java.lang.Class#forName(java.lang.String)
 * @see     java.lang.ClassLoader#findSystemClass(java.lang.String)
 * @see     java.lang.ClassLoader#loadClass(java.lang.String, boolean)
 * @since   1.0
 */
public class ClassNotFoundException extends ReflectiveOperationException {
    
use serialVersionUID from JDK 1.1.X for interoperability
/**
     * use serialVersionUID from JDK 1.1.X for interoperability
     */
     @java.io.Serial
     private static final long serialVersionUID = 9176873029745254542L;

    
Constructs a ClassNotFoundException with no detail message. /**
     * Constructs a {@code ClassNotFoundException} with no detail message.
     */
    public ClassNotFoundException() {
        super((Throwable)null);  // Disallow initCause
    }

    
Constructs a ClassNotFoundException with the specified detail message. 
Params:
s –   the detail message./**
     * Constructs a {@code ClassNotFoundException} with the
     * specified detail message.
     *
     * @param   s   the detail message.
     */
    public ClassNotFoundException(String s) {
        super(s, null);  //  Disallow initCause
    }

    
Constructs a ClassNotFoundException with the specified detail message and optional exception that was raised while loading the class. 
Params:
s – the detail message
ex – the exception that was raised while loading the class
Since:
1.2/**
     * Constructs a {@code ClassNotFoundException} with the
     * specified detail message and optional exception that was
     * raised while loading the class.
     *
     * @param s the detail message
     * @param ex the exception that was raised while loading the class
     * @since 1.2
     */
    public ClassNotFoundException(String s, Throwable ex) {
        super(s, ex);  //  Disallow initCause
    }

    
Returns the exception that was raised if an error occurred while attempting to load the class. Otherwise, returns null. 
API Note:
 This method predates the general-purpose exception chaining facility. The Throwable.getCause() method is now the preferred means of obtaining this information.
Returns:
the Exception that was raised while loading a class
Since:
1.2/**
     * Returns the exception that was raised if an error occurred while
     * attempting to load the class. Otherwise, returns {@code null}.
     *
     * @apiNote
     * This method predates the general-purpose exception chaining facility.
     * The {@link Throwable#getCause()} method is now the preferred means of
     * obtaining this information.
     *
     * @return the {@code Exception} that was raised while loading a class
     * @since 1.2
     */
    public Throwable getException() {
        return super.getCause();
    }

    
Serializable fields for ClassNotFoundException.
@serialField
ex Throwable the Throwable/**
     * Serializable fields for ClassNotFoundException.
     *
     * @serialField ex Throwable  the {@code Throwable}
     */
    @java.io.Serial
    private static final ObjectStreamField[] serialPersistentFields = {
        new ObjectStreamField("ex", Throwable.class)
    };

    
Reconstitutes the ClassNotFoundException instance from a stream
and initialize the cause properly when deserializing from an older
version.
The getException and getCause method returns the private "ex" field
in the older implementation and ClassNotFoundException::cause
was set to null.
Params:
s – the ObjectInputStream from which data is read
Throws:
IOException – if an I/O error occurs
ClassNotFoundException – if a serialized class cannot be loaded/**
     * Reconstitutes the ClassNotFoundException instance from a stream
     * and initialize the cause properly when deserializing from an older
     * version.
     *
     * The getException and getCause method returns the private "ex" field
     * in the older implementation and ClassNotFoundException::cause
     * was set to null.
     *
     * @param  s the {@code ObjectInputStream} from which data is read
     * @throws IOException if an I/O error occurs
     * @throws ClassNotFoundException if a serialized class cannot be loaded
     */
    @java.io.Serial
    private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException {
        ObjectInputStream.GetField fields = s.readFields();
        Throwable exception = (Throwable) fields.get("ex", null);
        if (exception != null) {
            setCause(exception);
        }
    }

    
To maintain compatibility with older implementation, write a serial
"ex" field with the cause as the value.
Params:
out – the ObjectOutputStream to which data is written
Throws:
IOException – if an I/O error occurs/**
     * To maintain compatibility with older implementation, write a serial
     * "ex" field with the cause as the value.
     *
     * @param  out the {@code ObjectOutputStream} to which data is written
     * @throws IOException if an I/O error occurs
     */
    @java.io.Serial
    private void writeObject(ObjectOutputStream out) throws IOException {
        ObjectOutputStream.PutField fields = out.putFields();
        fields.put("ex", super.getCause());
        out.writeFields();
    }
}