Android关于获取时间的记录(小结)

 public class MainActivity extends AppCompatActivity { public static final String TAG = "MainActivity"; @RequiresApi(api = Build.VERSION_CODES.CUPCAKE) @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //timestamp TextView timestamp = findViewById(R.id.timestamp_show); timestamp.setText("timestamp:" + System.currentTimeMillis()); //date Date date = new Date(); TextView date_show = findViewById(R.id.date_show); date_show.setText("Date:" + date.toString()); //Calendar TextView calendar_show = findViewById(R.id.calendar_show); Calendar calendar = Calendar.getInstance(); int year = calendar.get(Calendar.YEAR); int month = calendar.get(Calendar.MONTH); int day = calendar.get(Calendar.DATE); int hour = calendar.get(Calendar.HOUR); int minute = calendar.get(Calendar.MINUTE); int second = calendar.get(Calendar.SECOND); String calendar_show_string = "Calendar:" + year + "-" + month + "-" + day + " " + hour + ":" + minute + ":" + second; calendar_show.setText(calendar_show_string); //Time TextView time_show = findViewById(R.id.time_show); Time time = new Time(); time.setToNow(); int time_year = time.year; int time_month = time.month; int time_day = time.monthDay; int time_hour = time.hour; int time_minute = time.minute; int time_second = time.second; String time_show_string = "Time:" + time_year + "-" + time_month + "-" + time_day + " " + time_hour + ":" + time_minute + ":" + time_second; time_show.setText(time_show_string); //SimpleDateFormat TextView simpleDateFormat_show = findViewById(R.id.simpleDateFormat_show); SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String simpleDateFormat_tring = "SimpleDateFormat:" + format.format(new Date()); simpleDateFormat_show.setText(simpleDateFormat_tring); Log.d(TAG, "onCreate: Long的最大值：" + Long.MAX_VALUE); }

 //timestamp TextView timestamp = findViewById(R.id.timestamp_show); timestamp.setText("timestamp:" + System.currentTimeMillis());

 /** * Returns the current time in milliseconds. Note that * while the unit of time of the return value is a millisecond, * the granularity of the value depends on the underlying * operating system and may be larger. For example, many * operating systems measure time in units of tens of * milliseconds. * * 
 See the description of the class Date for * a discussion of slight discrepancies that may arise between * "computer time" and coordinated universal time (UTC). * * @return the difference, measured in milliseconds, between *   the current time and midnight, January 1, 1970 UTC. * @see  java.util.Date */ public static native long currentTimeMillis();

 //date Date date = new Date(); TextView date_show = findViewById(R.id.date_show); date_show.setText("Date:" + date.toString());

 public Date() { this(System.currentTimeMillis()); } public Date(long date) { fastTime = date; } /** * @param year the year minus 1900. * @param month the month between 0-11. * @param date the day of the month between 1-31. * @param hrs  the hours between 0-23. * @param min  the minutes between 0-59. * @param sec  the seconds between 0-59. * @see  java.util.Calendar * @deprecated As of JDK version 1.1, * replaced by Calendar.set(year + 1900, month, date, * hrs, min, sec) or GregorianCalendar(year + 1900, * month, date, hrs, min, sec). */ @Deprecated public Date(int year, int month, int date, int hrs, int min, int sec) { int y = year + 1900; // month is 0-based. So we have to normalize month to support Long.MAX_VALUE. if (month >= 12) { y += month / 12; month %= 12; } else if (month <0) { y += CalendarUtils.floorDivide(month, 12); month = CalendarUtils.mod(month, 12); } BaseCalendar cal = getCalendarSystem(y); cdate = (BaseCalendar.Date) cal.newCalendarDate(TimeZone.getDefaultRef()); cdate.setNormalizedDate(y, month + 1, date).setTimeOfDay(hrs, min, sec, 0); getTimeImpl(); cdate = null; }

 //SimpleDateFormat TextView simpleDateFormat_show = findViewById(R.id.simpleDateFormat_show); SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String simpleDateFormat_tring = "SimpleDateFormat:" + format.format(new Date()); simpleDateFormat_show.setText(simpleDateFormat_tring);

 /** * Date formats are not synchronized. * It is recommended to create separate format instances for each thread. * If multiple threads access a format concurrently, it must be synchronized * externally. */

 //Calendar TextView calendar_show = findViewById(R.id.calendar_show); Calendar calendar = Calendar.getInstance(); int year = calendar.get(Calendar.YEAR); int month = calendar.get(Calendar.MONTH); int day = calendar.get(Calendar.DATE); int hour = calendar.get(Calendar.HOUR); int minute = calendar.get(Calendar.MINUTE); int second = calendar.get(Calendar.SECOND); String calendar_show_string = "Calendar:" + year + "-" + month + "-" + day + " " + hour + ":" + minute + ":" + second; calendar_show.setText(calendar_show_string);

 public final static int ERA = 0; public final static int YEAR = 1; public final static int MONTH = 2; public final static int WEEK_OF_YEAR = 3; ... @SuppressWarnings("ProtectedField") protected int fields[]; public int get(int field) { complete(); return internalGet(field); } protected final int internalGet(int field) { return fields[field]; }

 //Time TextView time_show = findViewById(R.id.time_show); Time time = new Time(); time.setToNow(); int time_year = time.year; int time_month = time.month; int time_day = time.monthDay; int time_hour = time.hour; int time_minute = time.minute; int time_second = time.second; String time_show_string = "Time:" + time_year + "-" + time_month + "-" + time_day + " " + time_hour + ":" + time_minute + ":" + time_second; time_show.setText(time_show_string);

 /** * An alternative to the {@link java.util.Calendar} and * {@link java.util.GregorianCalendar} classes. An instance of the Time class represents * a moment in time, specified with second precision. It is modelled after * struct tm. This class is not thread-safe and does not consider leap seconds. */