Byte to megabyte conversion doesn't work

Question

i need convert the byte in Megabyte in my application but something is wrong.. First of all, i need display for example 1.2MB and not 1MB.. now, i have this declaration:

public long mStartRX = 0;

then in the onCreate

mStartRX = TrafficStats.getTotalRxBytes();

finally this to find the data usage in byte:

final long rxBytes = TrafficStats.getTotalRxBytes()- mStartRX;
        RX.setText(Long.toString(rxBytes) + " " + "Bytes");

i tryied this solution:

final long rxBytes = TrafficStats.getTotalRxBytes()/(1024*1024)- mStartRX;
        RX.setText(Long.toString(rxBytes) + " " + "Bytes");

but the result is not correct.. Infact i display something like: -1258912654 and of course it's not correct. How can i solve the problem?

Uhm, maybe like `(TrafficStats.getTotalRxBytes() - mStartRX) / (1024*1024)` ? — zapl, Nov 11 '13 at 19:59
I was thinking the same solution but it display 0.0MB forever :( — David_D, Nov 11 '13 at 20:02

hakanostrom · Accepted Answer · 2013-11-11T20:15:43.580

3

It takes some math skills here I think, and also knowledge of integer/floatingpoint division. But this code should work

long mStartRX = TrafficStats.getTotalRxBytes();
...
long rxBytes = TrafficStats.getTotalRxBytes()- mStartRX;

RX.setText(rxBytes + " Bytes");
RX.setText(String.format("%.2f MB",rxBytes /(1024f*1024f)));

The String.format is used to get exactly 2 decimals (%.2f) from a floating point varible/expression. Also "1024f" means 1024 in float, because we want floating point division, not integer division.

Edit

To save it in variable

float rxMBytes = rxBytes/(1024f*1024f);
RX.setText(String.format("%.2f MB",rxMBytes ));

edited Nov 11 '13 at 20:15

answered Nov 11 '13 at 20:02

hakanostrom

1,081
8
15

Could be possible recevie 255,85 MB? I'm display the total MB (3g+wifi) – David_D Nov 11 '13 at 20:08
and is it possible save in a variable the value in mb? like `RXMB = (String.format("%.2f MB",rxBytes /(1024f*1024f)));` or something like that. – David_D Nov 11 '13 at 20:11
Impossible to say ´cause I have no clue what you are measuring (in place of the dots). – hakanostrom Nov 11 '13 at 20:12
because i need insert this value in a setValue position like here: `d2.setValue(txBytes);` – David_D Nov 11 '13 at 20:13

Byte to megabyte conversion doesn't work

1 Answers1