[Views] A utility class to do batch operations on multiple views #tags: android, view, utility

Views.java

/*
 * Copyright (C) 2017 Subinkrishna Gopi
 *
 * 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.
 */

import android.support.annotation.NonNull;
import android.view.View;

/**
 * Collection of utility methods for {@link android.view.View}
 *
 * @author Subinkrishna Gopi
 */
public class Views {

    /* Private constructor */
    private Views() {
        throw new RuntimeException("Invalid operation!");
    }

    /**
     * Action interface definition.
     *
     * @param <T>
     */
    public interface Action<T> {
        void call(@NonNull T t);
    }

    /* Show */
    public static Action<View> SHOW = new Action<View>() {
        @Override public void call(View v) {
            v.setVisibility(View.VISIBLE);
        }
    };

    /* Hide */
    public static Action<View> HIDE = new Action<View>() {
        @Override public void call(View v) {
            v.setVisibility(View.GONE);
        }
    };

    /* Enable */
    public static Action<View> ENABLE = new Action<View>() {
        @Override public void call(View v) {
            v.setEnabled(true);
        }
    };

    /* Disable */
    public static Action<View> DISABLE = new Action<View>() {
        @Override public void call(View v) {
            v.setEnabled(false);
        }
    };

    /**
     * Applies the specified action to all the supplied views.
     *
     * @param action
     * @param views
     * @param <T>
     */
    @SafeVarargs @SuppressWarnings("unused")
    public static <T extends View> void apply(Action<T> action, T... views) {
        if ((null != action) && (null != views) && (views.length > 0)) {
            for (View v : views) {
                if (null != v) action.call((T)v);
            }
        }
    }

    /**
     * Sets the visibility of all the supplied views based on the flag.
     *
     * @param show  {@code true} to make all views visible, {@code false} to hide
     * @param views
     * @param <T>
     */
    @SafeVarargs @SuppressWarnings("unused")
    public static <T extends View> void show(boolean show, T... views) {
        apply(show ? SHOW : HIDE, views);
    }

    /**
     * Sets the visibility of all the supplied views to {@link View#VISIBLE}
     *
     * @param views
     * @param <T>
     */
    @SafeVarargs @SuppressWarnings("unused")
    public static <T extends View> void show(T... views) {
        apply(SHOW, views);
    }

    /**
     * Sets the visibility of all the supplied views to {@link View#GONE}
     *
     * @param views
     * @param <T>
     */
    @SafeVarargs @SuppressWarnings("unused")
    public static <T extends View> void hide(T... views) {
        apply(HIDE, views);
    }

    /**
     * Enables all the supplied views based on the flag.
     *
     * @param show  {@code true} to enable all views, {@code false} to disable
     * @param views
     * @param <T>
     */
    @SafeVarargs @SuppressWarnings("unused")
    public static <T extends View> void enable(boolean show, T... views) {
        apply(show ? ENABLE : DISABLE, views);
    }

    /**
     * Attaches the given {@link android.view.View.OnClickListener} to all the aupplied {@link View}
     * instances.
     *
     * @param listener
     * @param views
     * @param <T>
     */
    @SafeVarargs @SuppressWarnings("unused")
    public static <T extends View> void onClickListener(final View.OnClickListener listener,
                                                        T... views) {
        if ((null != views) && (views.length > 0)) {
            apply(new Action<View>() {
                @Override public void call(View v) {
                    v.setOnClickListener(listener);
                }
            }, views);
        }
    }
}

Views.java - Usage

// Built-in actions
Views.show(v1, v2, v3);
Views.show(false, v1, v2, v3);
Views.hide(v1, v2, v3);
Views.enable(true, v1, v2, v3);

// Custom Actions
// 1.7
Views.apply(new Action<View> {
    public void call(View v) {
        v.setOnClickListener(listener);
    },
    v1, v2, v3
});

// 1.8
Views.apply(v -> v.setOnClickListener(listener), v1, v2, v3);