java.util.Calendar

java.util.Calendar is an abstract base class for converting between a Date object and a set of integer fields such as YEAR, MONTH, DAY, HOUR, and so on.

Example of usage of Calendar.

package com.exercise.AndroidCalendar;

import java.util.Calendar;
import java.util.Locale;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class AndroidCalendarActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        TextView prompt = new TextView(this);
        setContentView(prompt);
        prompt.setText(getCalendarPrompt());
    }
    
    private String getCalendarPrompt(){
     Calendar rightNow = Calendar.getInstance();
     
     String p = rightNow + "\n\n"
       + rightNow.get(Calendar.YEAR) + "-"
       + rightNow.getDisplayName(Calendar.MONTH, Calendar.SHORT, Locale.US) + "-"
       + rightNow.get(Calendar.DATE) + "\n"
       + "DAY_OF_YEAR: " + rightNow.get(Calendar.DAY_OF_YEAR) + "\n"
       + "DAY_OF_MONTH: " + rightNow.get(Calendar.DAY_OF_MONTH) + "\n"
       + "DAY_OF_WEEK: " + rightNow.get(Calendar.DAY_OF_WEEK) + "\n"
       + "\n"
       + "getTime(): " + rightNow.getTime() + "\n"
       + "getTimeInMillis(): " + rightNow.getTimeInMillis() + "\n"
       + "\n";
     
     return p;
    }
}

Related:
- Get the difference between two Calendar