Utility class that helps with fragment manipulation

FragmentUtils.java

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;

/**
 * Utility class that helps with fragment manipulation.
 */

public class FragmentUtils {

    /**
     * Adds a fragment into the desired container.
     *
     * @param manager     Fragment Manager
     * @param containerId Id of the container
     * @param fragment    Fragment to be added
     * @param tag         Fragment tag
     */
    public static void addFragment(FragmentManager manager, int containerId, Fragment fragment, String tag) {
        if (!manager.isStateSaved()) {
            manager.beginTransaction()
                    .add(containerId, fragment, tag)
                    .commit();
        }
    }

    /**
     * Replaces the container content with the desired fragment.
     *
     * @param manager     Fragment Manager
     * @param containerId Id of the container
     * @param fragment    Fragment that will replace the current content
     * @param tag         Fragment tag
     */
    public static void replaceFragment(FragmentManager manager, int containerId, Fragment fragment, String tag) {
        if (!manager.isStateSaved()) {
            manager.beginTransaction()
                    .replace(containerId, fragment, tag)
                    .addToBackStack(tag)
                    .commit();
        }
    }

    /**
     * Removes a fragment by tag
     *
     * @param manager Fragment Manager
     * @param tag     Fragment tag
     */
    public static void removeFragment(FragmentManager manager, String tag) {
        Fragment fragment = manager.findFragmentByTag(tag);
        if (!manager.isStateSaved() && fragment != null) {
            manager.beginTransaction().remove(fragment).commit();
        }
    }

    /**
     * Returns a fragment of the specified type if found in the fragment manager and is instance of the desired type, null otherwise.
     *
     * @param manager       Fragment Manager
     * @param fragmentClass Fragment type
     * @param tag           Fragment tag
     * @param <T>           Fragment type
     * @return Fragment of T type
     */
    public static <T> T getFragmentByTag(FragmentManager manager, Class<T> fragmentClass, String tag) {
        Fragment fragment = manager.findFragmentByTag(tag);

        if (fragment != null) {
            if (fragment.getClass().isAssignableFrom(fragmentClass)) {
                return fragmentClass.cast(fragment);
            } else if (fragment.getClass().getSuperclass().isAssignableFrom(fragmentClass)) {
                return (T) fragment;
            }
        }

        return null;
    }

}