release memory, override by child activity. - Android Hardware

Android examples for Hardware:Memory

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Description

release memory, override by child activity.

Demo Code


//package com.java2s;
import android.app.Activity;

import android.view.View;
import android.view.ViewGroup;

import android.webkit.WebView;
import android.widget.ImageView;

public class Main {
    /**/* w  ww  .ja  va 2 s  . c  o  m*/
     * This function used for release memory, override by child activity.
     * 
     * @param activity
     *            The context.
     * @param viewID
     *            The id of root view.
     * */

    public static void cleanupView(Activity activity, int viewID) {
        try {
            View view = activity.findViewById(viewID);
            if (view != null) {
                unbindViewReferences(view);
                if (view instanceof ViewGroup)
                    unbindViewGroupReferences((ViewGroup) view);
            }
            System.gc();
        } catch (Throwable e) {

            // whatever exception is thrown just ignore it because a crash is
            // always worse than this method not doing what it's supposed to do
        }
    }

    /**
     * This method used for unbind reference to one view.
     * 
     * @param viewGroup
     *            The view.
     * */
    private static void unbindViewReferences(View view) {

        // set all listeners to null (not every view and not every API level
        // supports the methods)
        try {
            view.setOnClickListener(null);
        } catch (Throwable mayHappen) {
        }

        try {
            view.setOnCreateContextMenuListener(null);
        } catch (Throwable mayHappen) {
        }

        try {
            view.setOnFocusChangeListener(null);
        } catch (Throwable mayHappen) {
        }

        try {
            view.setOnKeyListener(null);
        } catch (Throwable mayHappen) {
        }

        try {
            view.setOnLongClickListener(null);
        } catch (Throwable mayHappen) {
        }

        try {
            view.setOnClickListener(null);
        } catch (Throwable mayHappen) {
        }

        // set background to null
        setNullLayout(view);
        if (view instanceof ImageView) {
            ImageView imageView = (ImageView) view;
            if (imageView != null) {
                setNullViewDrawable(imageView);
            }
        }

        // destroy webview
        if (view instanceof WebView) {
            ((WebView) view).destroy();
        }
    }

    /**
     * This method used for unbind reference to view group.
     * 
     * @param viewGroup
     *            The group of views.
     * */
    private static void unbindViewGroupReferences(ViewGroup viewGroup) {
        int nrOfChildren = viewGroup.getChildCount();
        for (int i = 0; i < nrOfChildren; i++) {
            View view = viewGroup.getChildAt(i);
            unbindViewReferences(view);
            if (view instanceof ViewGroup)
                unbindViewGroupReferences((ViewGroup) view);
        }
        try {
            viewGroup.removeAllViews();
        } catch (Throwable mayHappen) {

            // AdapterViews, ListViews and potentially other ViewGroups don't
            // support the removeAllViews operation
        }
    }

    /**
     * Set null view.
     * 
     * @param pview
     */
    public static void setNullLayout(View pview) {
        if (pview != null) {
            pview.setBackgroundDrawable(null);
            pview.setBackgroundResource(0);
            pview.destroyDrawingCache();
        }
    }

    /**
     * Set null Image view.
     * 
     * @param view
     *            The {@link ImageView}
     */
    public static void setNullViewDrawable(ImageView view) {

        // remove resource of View.
        if (view != null) {

            if (view.getDrawable() != null) {
                view.getDrawable().setCallback(null);
            }
            if (view.getBackground() != null) {
                view.getBackground().setCallback(null);
            }
            view.setImageDrawable(null);
            view.getResources().flushLayoutCache();
            view.destroyDrawingCache();
            view.setBackgroundDrawable(null);
            view.setBackgroundResource(0);
            view = null;
        }
    }
}

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