io.bretty.console.view.MenuView Maven / Gradle / Ivy

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A Java framework to instantly build the View layer of your command line app. No more worries about anything like printing menus or validating user inputs. Just focus on your app logic.

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package io.bretty.console.view;

import java.util.ArrayList;
import java.util.InputMismatchException;
import java.util.List;

/**
 * The View that displays a list of options with index numbers, and asks the user to select one to proceed. It provides validation of user input.
 */

public class MenuView extends AbstractView {

    /**
     * a list of {@code AbstractView} objects to be displayed in the menu as available options
     */
    protected List menuItems = new ArrayList<>();

    private IndexNumberFormatter indexNumberFormatter = DefaultIndexNumberFormatter.INSTANCE;

    public MenuView(String runningTitle, String nameInParentMenu) {
        super(runningTitle, nameInParentMenu);
    }

    public MenuView(String runningTitle, String nameInParentMenu, ViewConfig viewConfig) {
        super(runningTitle, nameInParentMenu, viewConfig);
    }

    /**
     * Add an entry to the menu; similar to remove, setter and getter
     *
     * @param menuItem to be appended to the last
     */
    public void addMenuItem(AbstractView menuItem) {
        menuItem.parentView = this;
        this.menuItems.add(menuItem);
    }

    public void removeMenuItem(int index) {
        this.menuItems.remove(index);
    }

    public void removeMenuItem(AbstractView menuItem){
        this.menuItems.remove(menuItem);
    }

    public List getMenuItems() {
        return new ArrayList<>(this.menuItems);
    }

    public void setMenuItems(List menuItems) {
        this.menuItems = new ArrayList<>(menuItems);
    }

    private boolean isValidIndex(int index) {
        return index >= 1 && index <= this.menuItems.size() + 1;
    }

    @Override
    public void display() {

        this.println();

        // print running title (e.g. "Create Item")
        this.println(this.runningTitle);

        // print all menu items
        // e.g.
        // 1) Create Item
        // 2) View Item
        // 3) ...

        for (int i = 0; i < this.menuItems.size(); ++i) {
            this.println(this.indexNumberFormatter.format(i) + this.menuItems.get(i).nameInParentMenu);
        }

        String backOrQuit = this.parentView == null ? this.viewConfig.getQuitMenuName() : this.viewConfig.getBackMenuName();

        // 4) Back/quit; always the last index
        this.println(this.indexNumberFormatter.format(this.menuItems.size()) + backOrQuit);


        // get a valid index number
        Validator indexNumberValidator = new Validator() {
            @Override
            public boolean isValid(Integer index) {
                return isValidIndex(index);
            }
        };

        int selection = this.prompt(this.viewConfig.getMenuSelectionMessage(), Integer.class, indexNumberValidator);

        // go parentView
        if (selection == this.menuItems.size() + 1) {
            this.goBack();
        } else {
            this.menuItems.get(selection - 1).display();
        }
    }

}