import gnu.trove.stack.TDoubleStack; //导入依赖的package包/类
/**
 * Creates a new <code>TDoubleArrayStack</code> instance that is
 * a copy of the instanced passed to us.
 *
 * @param stack the instance to copy
 */
public TDoubleArrayStack( TDoubleStack stack ) {
    if ( stack instanceof TDoubleArrayStack ) {
        TDoubleArrayStack array_stack = ( TDoubleArrayStack ) stack;
        this._list = new TDoubleArrayList( array_stack._list );
    } else {
        throw new UnsupportedOperationException( "Only support TDoubleArrayStack" );
    }
}