Android example source code file (DebugUtils.java)

This example Android source code file (DebugUtils.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android_object_filter, class, debugutils, illegalaccessexception, invocationtargetexception, method, nosuchmethodexception, object, reflection, string

The DebugUtils.java Android example source code

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * 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.
 */

package android.util;

import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;

/**
 * <p>Various utilities for debugging and logging.
 
 */
public class DebugUtils {
    /**
     * <p>Filters objects against the ANDROID_OBJECT_FILTER
     * environment variable. This environment variable can filter objects
     * based on their class name and attribute values.</p>
     *
     * <p>Here is the syntax for ANDROID_OBJECT_FILTER:

     *
     * <p>ClassName@attribute1=value1@attribute2=value2...

     *
     * <p>Examples:

     * <ul>
     * <li>Select TextView instances: TextView
     * <li>Select TextView instances of text "Loading" and bottom offset of 22:
     * <code>TextView@text=Loading.*@bottom=22
     * </ul>
     *
     * <p>The class name and the values are regular expressions.

     *
     * <p>This class is useful for debugging and logging purpose:

     * <pre>
     * if (DEBUG) {
     *   if (DebugUtils.isObjectSelected(childView) && LOGV_ENABLED) {
     *     Log.v(TAG, "Object " + childView + " logged!");
     *   }
     * }
     * </pre>
     *
     * <p>NOTE: This method is very expensive as it relies
     * heavily on regular expressions and reflection. Calls to this method
     * should always be stripped out of the release binaries and avoided
     * as much as possible in debug mode.</p>
     *
     * @param object any object to match against the ANDROID_OBJECT_FILTER
     *        environement variable
     * @return true if object is selected by the ANDROID_OBJECT_FILTER
     *         environment variable, false otherwise
     */
    public static boolean isObjectSelected(Object object) {
        boolean match = false;
        String s = System.getenv("ANDROID_OBJECT_FILTER");
        if (s != null && s.length() > 0) {
            String[] selectors = s.split("@");
            // first selector == class name
            if (object.getClass().getSimpleName().matches(selectors[0])) {
                // check potential attributes
                for (int i = 1; i < selectors.length; i++) {
                    String[] pair = selectors[i].split("=");
                    Class<?> klass = object.getClass();
                    try {
                        Method declaredMethod = null;
                        Class<?> parent = klass;
                        do {
                            declaredMethod = parent.getDeclaredMethod("get" +
                                    pair[0].substring(0, 1).toUpperCase() +
                                    pair[0].substring(1),
                                    (Class[]) null);
                        } while ((parent = klass.getSuperclass()) != null &&
                                declaredMethod == null);

                        if (declaredMethod != null) {
                            Object value = declaredMethod
                                    .invoke(object, (Object[])null);
                            match |= (value != null ?
                                    value.toString() : "null").matches(pair[1]);
                        }
                    } catch (NoSuchMethodException e) {
                        e.printStackTrace();
                    } catch (IllegalAccessException e) {
                        e.printStackTrace();
                    } catch (InvocationTargetException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
        return match;
    }

}