Android -- 内存泄漏

# Define the oom_adj values for the classes of processes that can be
# killed by the kernel.  These are used in ActivityManagerService.
    setprop ro.FOREGROUND_APP_ADJ 0
    setprop ro.VISIBLE_APP_ADJ 1
    setprop ro.SECONDARY_SERVER_ADJ 2
    setprop ro.BACKUP_APP_ADJ 2
    setprop ro.HOME_APP_ADJ 4
    setprop ro.HIDDEN_APP_MIN_ADJ 7
    setprop ro.CONTENT_PROVIDER_ADJ 14
    setprop ro.EMPTY_APP_ADJ 15
 
# Define the memory thresholds at which the above process classes will
# be killed.  These numbers are in pages (4k).
    setprop ro.FOREGROUND_APP_MEM 1536
    setprop ro.VISIBLE_APP_MEM 2048
    setprop ro.SECONDARY_SERVER_MEM 4096
    setprop ro.BACKUP_APP_MEM 4096
    setprop ro.HOME_APP_MEM 4096
    setprop ro.HIDDEN_APP_MEM 5120
    setprop ro.CONTENT_PROVIDER_MEM 5632
    setprop ro.EMPTY_APP_MEM 6144
 
# Write value must be consistent with the above properties.
# Note that the driver only supports 6 slots, so we have HOME_APP at the
# same memory level as services.
    write /sys/module/lowmemorykiller/parameters/adj 0,1,2,7,14,15
 
    write /proc/sys/vm/overcommit_memory 1
    write /proc/sys/vm/min_free_order_shift 4
    write /sys/module/lowmemorykiller/parameters/minfree 1536,2048,4096,5120,5632,6144
 
    # Set init its forked children‘s oom_adj.
    write /proc/1/oom_adj -16

Cursor cursor = getContentResolver().query(uri ...);
if (cursor.moveToNext()) {
    ... ... 
}

Cursor cursor = null;
try {
    cursor = getContentResolver().query(uri ...);
    if (cursor != null && cursor.moveToNext()) {
        ... ... 
    }
} finally {
    if (cursor != null) {
        try { 
            cursor.close();
        } catch (Exception e) {
            //ignore this
        }
    }
}

public View getView(int position, View convertView, ViewGroup parent) {
    View view = new Xxx(...);
    ... ...
    return view;
}

public View getView(int position, View convertView, ViewGroup parent) {
    View view = null;
    if (convertView != null) {
        view = convertView;
        populate(view, getItem(position));
        ...
    } else {
        view = new Xxx(...);
        ...
    }
    return view;
}

/**
     * Free up the memory associated with this bitmap‘s pixels, and mark the
     * bitmap as "dead", meaning it will throw an exception if getPixels() or
     * setPixels() is called, and will draw nothing. This operation cannot be
     * reversed, so it should only be called if you are sure there are no
     * further uses for the bitmap. This is an advanced call, and normally need
     * not be called, since the normal GC process will free up this memory when
     * there are no more references to this bitmap.
     */

public class DemoActivity extends Activity {
    ... ...
    private Handler mHandler = ...
    private Object obj;
    public void operation() {
     obj = initObj();
     ...
     [Mark]
     mHandler.post(new Runnable() {
            public void run() {
             useObj(obj);
            }
     });
    }
}

... ...
public void operation() {
    obj = initObj();
    ...
    final Object o = obj;
    obj = null;
    mHandler.post(new Runnable() {
        public void run() {
            useObj(o);
        }
    }
}
... ...