com.tractionsoftware.gwt.user.client.ui.SingleListBox.java Source code

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Here is the source code for com.tractionsoftware.gwt.user.client.ui.SingleListBox.java

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/*
 * Copyright 2010 Traction Software, Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.tractionsoftware.gwt.user.client.ui;

import com.google.gwt.event.dom.client.ChangeEvent;
import com.google.gwt.event.dom.client.ChangeHandler;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.ui.HasValue;
import com.google.gwt.user.client.ui.ListBox;

/**
 * A subclass of ListBox representing a single select pulldown and
 * implementing HasValue<String>. It listens to its own ChangeEvent
 * and fires a ValueChangeEvent.
 */
public class SingleListBox extends ListBox implements HasValue<String> {

    private boolean addMissingValue;

    /**
     * Create a new SingleListBox with setAddMissingValue(true)
     */
    public SingleListBox() {
        this(true);
    }

    /**
     * Create a new SingleListBox
     */
    public SingleListBox(boolean addMissingValue) {
        this(addMissingValue, false);
    }

    protected SingleListBox(boolean addMissingValue, boolean isMultipleSelect) {
        super(isMultipleSelect);
        setAddMissingValue(addMissingValue);

        // Listen to our own change events and broadcast as
        // ValueChangeEvent<String>
        addChangeHandler(new ChangeHandler() {
            @Override
            public void onChange(ChangeEvent event) {
                ValueChangeEvent.fire(SingleListBox.this, getValue());
            }
        });
    }

    // ----------------------------------------------------------------------
    // 

    /**
     * Gets the current setting for add missing value.
     *
     * @return returns true if missing values will be added to the
     * ListBox when setValue is called.
     */
    public boolean getAddMissingValue() {
        return addMissingValue;
    }

    /**
     * Sets the current setting for add missing value.
     *
     * @param addMissingValue If true, when setValue is called, if the
     * item cannot be found in the list, it will be added
     * automatically to the end of the list.
     */
    public void setAddMissingValue(boolean addMissingValue) {
        this.addMissingValue = addMissingValue;
    }

    // ----------------------------------------------------------------------
    // HasValue implementation

    /**
     * Returns the current value selected in the ListBox.
     */
    @Override
    public String getValue() {
        return getSelectedValue(this);
    }

    /**
     * Selects the specified value in the list.
     * 
     * @param value the new value
     * @see #setAddMissingValue
     */
    @Override
    public void setValue(String value) {
        setValue(value, false);
    }

    /**
     * Selects the specified value in the list.
     * 
     * @param value the new value
     * @param fireEvents if true, a ValueChangeEvent event will be fired
     * @see #setAddMissingValue
     */
    @Override
    public void setValue(String value, boolean fireEvents) {
        boolean added = setSelectedValue(this, value, addMissingValue);
        if (added && fireEvents) {
            ValueChangeEvent.fire(this, getValue());
        }
    }

    /**
     * Finds the index of the specified value.
     *
     * @param value the value to find
     * @return returns the index of the value or -1 if the value was not found
     * in the ListBox
     */
    public int findValueIndex(String value) {
        return findValueInListBox(this, value);
    }

    @Override
    public HandlerRegistration addValueChangeHandler(ValueChangeHandler<String> handler) {
        return addHandler(handler, ValueChangeEvent.getType());
    }

    // ----------------------------------------------------------------------
    // utility functions for working with ListBox options

    /**
     * Utility function to get the current value.
     */
    public static final String getSelectedValue(ListBox list) {
        int index = list.getSelectedIndex();
        return (index >= 0) ? list.getValue(index) : null;
    }

    /**
     * Utility function to get the current text.
     */
    public static final String getSelectedText(ListBox list) {
        int index = list.getSelectedIndex();
        return (index >= 0) ? list.getItemText(index) : null;
    }

    /**
     * Utility function to find the first index of a value in a
     * ListBox.
     */
    public static final int findValueInListBox(ListBox list, String value) {
        for (int i = 0; i < list.getItemCount(); i++) {
            if (value.equals(list.getValue(i))) {
                return i;
            }
        }
        return -1;
    }

    /**
     * Utility function to set the current value in a ListBox.
     *
     * @return returns true if the option corresponding to the value
     * was successfully selected in the ListBox
     */
    public static final boolean setSelectedValue(ListBox list, String value, boolean addMissingValues) {
        if (value == null) {
            list.setSelectedIndex(0);
            return false;
        } else {
            int index = findValueInListBox(list, value);
            if (index >= 0) {
                list.setSelectedIndex(index);
                return true;
            }

            if (addMissingValues) {
                list.addItem(value, value);

                // now that it's there, search again
                index = findValueInListBox(list, value);
                list.setSelectedIndex(index);
                return true;
            }

            return false;
        }
    }

}