FirstFlag.java

package eu.europeana.cloud.common.utils;

/**
 * This is class to be used in common 'is this first time?' example.
 *
 * Because it provides {@link #unpack()} method, the user of this class does not
 * have to add <code>first = false</code> after checking its value.
 */
public class FirstFlag {

    private Boolean first = true;

    /**
     * Creates instance of FirstFlag.
     *
     * Object is initialised in the way that first {@link #unpack()} method call
     * will return <code>true</code> and next {@link #unpack()} method calls
     * will return <code>false</code>.
     */
    public FirstFlag() {

    }

    /**
     * Check if this is the first time.
     *
     * If this is the first call of this method for this object it will return
     * <code>true</code>, subsequent calls will return <code>false</code>.
     *
     * @return value indicating whether this is the first call of this method or
     * not
     */
    public Boolean unpack() {
        if (!first) {
            return false;
        }
        first = false;
        return true;
    }

    /**
     * Resets flag to original state.
     *
     * After calling this method, object returns to its original state. The next
     * call of {@link #unpack()} method will return <code>true</code> and
     * subsequent will again return <code>false</code>.
     */
    public void reset() {
        first = true;
    }
}