com.turbomanage.gwt.client.ui.widget.SelectOneListBox.java Source code

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Here is the source code for com.turbomanage.gwt.client.ui.widget.SelectOneListBox.java

Source

package com.turbomanage.gwt.client.ui.widget;

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.ListBox;

import java.util.ArrayList;
import java.util.Collection;

/**
 * A ListBox that can be populated with any Collection
 * 
 * Published under Apache License v2
 * 
 * @author David Chandler
 * @param <T>
 */
public class SelectOneListBox<T> extends ListBox implements HasSelectedValue<T> {

    public interface OptionFormatter<T> {
        abstract String getLabel(T option);

        abstract String getValue(T option);
    }

    private boolean valueChangeHandlerInitialized;
    private T[] options;
    private OptionFormatter<T> formatter;

    public SelectOneListBox(Collection<T> selections, OptionFormatter<T> formatter) {
        setSelections(selections);
        setFormatter(formatter);
    }

    public SelectOneListBox(OptionFormatter<T> formatter) {
        this(new ArrayList<T>(), formatter);
    }

    public void setFormatter(OptionFormatter<T> formatter) {
        this.formatter = formatter;
    }

    @SuppressWarnings("unchecked")
    @Override
    public void setSelections(Collection<T> selections) {
        // Remember selected value
        T selectedValue = getValue();
        // Remove prior options
        if (options != null) {
            int numItems = this.getItemCount();
            int firstOption = numItems - options.length;
            for (int i = firstOption; i < numItems; i++)
                this.removeItem(firstOption);
        }
        options = (T[]) selections.toArray();
        for (T option : options) {
            String optionLabel = formatter.getLabel(option);
            String optionValue = formatter.getValue(option);
            this.addItem(optionLabel, optionValue);
        }
        // Replace selected value
        setSelectedValue(selectedValue);
    }

    private void setSelectedValue(T value) {
        if (value == null)
            return;

        for (int i = 0; i < this.getItemCount(); i++) {
            String thisLabel = this.getItemText(i);
            if (formatter.getLabel(value).equals(thisLabel)) {
                this.setSelectedIndex(i);
                return;
            }
        }
        throw new IllegalArgumentException("No index found for value " + value.toString());
    }

    /*
     * Methods to implement HasValue 
     */

    @Override
    public T getValue() {
        if (getSelectedIndex() >= 0) {
            String name = getValue(getSelectedIndex());

            for (T option : options) {
                if (formatter.getValue(option).equals(name))
                    return option;
            }
        }

        return null;
    }

    @Override
    public void setValue(T value) {
        this.setValue(value, false);
    }

    @Override
    public void setValue(T value, boolean fireEvents) {
        T oldValue = getValue();
        this.setSelectedValue(value);
        if (fireEvents) {
            ValueChangeEvent.fireIfNotEqual(this, oldValue, value);
        }
    }

    @Override
    public void clearSelectedValue() {
        this.setSelectedIndex(0);
    }

    @Override
    public HandlerRegistration addValueChangeHandler(ValueChangeHandler<T> handler) {
        // Initialization code
        if (!valueChangeHandlerInitialized) {
            valueChangeHandlerInitialized = true;
            super.addChangeHandler(new ChangeHandler() {
                public void onChange(ChangeEvent event) {
                    ValueChangeEvent.fire(SelectOneListBox.this, getValue());
                }
            });
        }
        return addHandler(handler, ValueChangeEvent.getType());
    }

}