sbool.java

来自「OpenJMS是一个开源的Java Message Service API 1.」· Java 代码 · 共 164 行

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 */

package org.exolab.jms.selector;


/**
 * This class is an adapter for the Boolean type.
 *
 * @version     $Revision: 1.1 $ $Date: 2004/11/26 01:50:44 $
 * @author      <a href="mailto:[e-mail]">Tim Anderson</a>
 * @see         SObject
 */
class SBool extends SObject {

    /**
     * Boolean true
     */
    public static final SBool TRUE = new SBool(Boolean.TRUE);

    /**
     * Boolean false
     */
    public static final SBool FALSE = new SBool(Boolean.FALSE);

    /**
     * The wrapped value
     */
    private Boolean _value;


    /**
     * Construct a new <code>SBool</code>
     *
     * @param value the boolean value
     */
    public SBool(final Boolean value) {
        _value = value;
    }

    /**
     * Returns the value of this, wrapped in a <code>Boolean</code>
     *
     * @return the value of this, wrapped in a <code>Boolean</code>
     */
    public final Object getObject() {
        return _value;
    }

    /**
     * Returns the value of this
     *
     * @return the value of this
     */
    public final boolean value() {
        return _value.booleanValue();
    }

    /**
     * Evaluates <code>this AND rhs</code>
     *
     * @param rhs the right hand side of the expression. May be null
     * @return <code>SBool.TRUE</code> if <code>this</code> and
     * <code>rhs</code> are <code>true</code>, <code>SBool.FALSE</code>
     * if one is <code>false</code>, or <code>null</code> if <code>rhs</code>
     * is <code>null</code>
     */
    public final SBool and(final SBool rhs) {
        SBool result = null;
        if (rhs != null) {
            if (value() && rhs.value()) {
                result = SBool.TRUE;
            } else {
                result = SBool.FALSE;
            }
        } else if (!value()) {
            result = SBool.FALSE;
        }

        return result;
    }

    /**
     * Evaluates <code>this OR rhs</code>
     *
     * @param rhs the right hand side of the expression. May be null
     * @return <code>SBool.TRUE</code> if <code>this</code> is
     * <code>true</code>, otherwise <code>rhs</code>
     */
    public final SBool or(final SBool rhs) {
        SBool result = null;
        if (value()) {
            result = SBool.TRUE;
        } else {
            result = rhs;
        }
        return result;
    }

    /**
     * Evaluates <code>NOT this</code>
     *
     * @return <code>SBool.TRUE</code> if <code>this</code> is
     * <code>false</code>, otherwise <code>SBool.FALSE</code>
     */
    public final SBool not() {
        SBool result = SBool.TRUE;
        if (value()) {
            result = SBool.FALSE;
        }
        return result;
    }

    /**
     * Returns the type of this
     *
     * @return {@link Type#BOOLEAN}
     */
    public final Type type() {
        return Type.BOOLEAN;
    }

} //-- SBool