android内部内存使用情况

Question

I am new in Android and I want to find free memory in internal storage. I use two function to find free memory but they show me two different values in long format. I don't know why? Here is my code:

1) Result of getTIM() function is 558628864

public String getTIM(){
    File path = Environment.getDataDirectory();
    StatFs stat = new StatFs(path.getPath());
    long blockSize = stat.getBlockSize();
    long totalBlocks = stat.getBlockCount();
    String str = Long.toString(blockSize * totalBlocks);
    return str;
} 

2) Result of ITMStr() function is 914120704

public String ITMStr(){
    StatFs statFs = new StatFs(Environment.getRootDirectory().getAbsolutePath());
    long blockCount = statFs.getBlockCountLong();
    long blockSize = statFs.getBlockSizeLong();
    long total = blockCount * blockSize;
    String str = Long.toString(total);
    return str;
}

Which value is right?

Answer 1

According to reference :

public static File getDataDirectory ()

Added in API level 1 Return the user data directory.

_

public static File getRootDirectory ()

Added in API level 1 Return root of the "system" partition holding the core Android OS. Always present and mounted read-only.

So sizes are different as you are getting sizes for different stuff.