Oxygen Monitor Full Code

Note that the first line (the package name) will depend on what you named your application.

package org.spaceskills.oxygauge;

import android.app.Activity;
import android.graphics.Color;
import android.graphics.PorterDuff;
import android.os.CountDownTimer;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;


public class MainActivity extends Activity {

    private ProgressBar pgOxy;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.

        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.

        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    // Takes a number of seconds
    // Returns formatted minutes and seconds
    private String convertTime (int seconds){

        // Convert to whole minutes and seconds remaining
        int minutes = (int) Math.floor(seconds / 60);
        seconds = seconds - (minutes*60);

        // Format, padding single digit seconds with a zero
        String formatted = String.valueOf(minutes) + ":";
        if (seconds < 10) formatted += "0";
        formatted += String.valueOf(seconds);

        return formatted;   // Return result
    }

    public void startUsingOxygen (View v){

        // Get references to the user interface elements
        EditText txtVolume = (EditText) findViewById(R.id.editText);
        TextView txtTime = (TextView) findViewById(R.id.textView);

        // Read volume, and set a default value if empty
        String volumeText = txtVolume.getText().toString();
        if ( volumeText.isEmpty() ) volumeText = "0";

        // Convert text entered into a number (volume), and
        // calculate the time that would allow (at 0.83ltr per minute)
        double volume = Double.valueOf( volumeText );
        if (volume < 0) volume = 0;
        double time = volume / 0.83;

        // Display the time in minutes - formatted to 2 decimal places
        txtTime.setText( convertTime( (int)(time*60) ) );

        // Get reference to progress bar in interface
        pgOxy = (ProgressBar) findViewById(R.id.progressBar);

        // Reset everything
        TextView warning = (TextView) findViewById(R.id.textView2);
        warning.setText("");
        pgOxy.getProgressDrawable().setColorFilter(Color.GREEN, PorterDuff.Mode.SRC_IN);

        // Convert time (currently in minutes) to seconds
        int s = (int) Math.ceil(time * 60.0);

        // Set the progress bar maximum
        pgOxy.setMax(s);

        // Create a CountDownTimer. Takes:

        //  number of milliseconds to count for in total (s*1000)
        //  time interval between ticks (1000 milliseconds = 1 sec)
        new CountDownTimer(s * 1000, 1000) {

            public void onTick(long millisUntilFinished) {

                int secUntilFinished = (int) millisUntilFinished / 1000;

                // Show current progress - how long till finished?
                pgOxy.setProgress(secUntilFinished);

                TextView txtTime = (TextView) findViewById(R.id.textView);
                txtTime.setText( convertTime( secUntilFinished ) );

                // If less than 30 seconds left, then raise alarm
                if (secUntilFinished < 30) {
                    pgOxy.getProgressDrawable().setColorFilter(Color.RED, PorterDuff.Mode.SRC_IN);
                    TextView warning = (TextView) findViewById(R.id.textView2);

                    // Flash warning on and off (based on whether even number of seconds)
                    if (secUntilFinished % 2 == 0) warning.setText("OXYGEN LOW!");
                    else warning.setText("** OXYGEN LOW! **");
                }
            }

            public void onFinish() {
                // Tidy up at the end
                pgOxy.setProgress(0);
                TextView warning = (TextView) findViewById(R.id.textView2);
                warning.setText("OXYGEN DEPLETED!");
                TextView txtTime = (TextView) findViewById(R.id.textView);
                txtTime.setText( "0:00" );
            }
        }.start();
    }

}