Question

In camera.java, I need to get property in system. However, I can’t import android.os.SystemProperties, compile camera always complains:

packages/apps/Camera/src/com/android/camera/Camera.java:53: cannot find symbol
symbol  : class SystemProperties
location: package android.os
import android.os.SystemProperties;

In the beginning of camera.java, I included:

import android.os.Message;
import android.os.MessageQueue;
import android.os.SystemClock;
import android.os.SystemProperties; /* (this is in line 53)*/

It seems SystemProperties is not in android.os package, but I have checked the frameworks source code, it’s indeed in it.

This happen in camera app. I found many apps under packages/app dir using SystemProperties in this manner. It’s really strange.

Answer 1

SystemProperties class is setted ‘hide’ annotation.
So you want to use this class in application layer,
you have to use refelection.

the definition of SystemProperties class is below.

package android.os;
/**
 * Gives access to the system properties store.  The system properties
 * store contains a list of string key-value pairs.
 *
 * {@hide}
 */
public class SystemProperties