The below code is to check the day of the week, now I want to check the date, month, year ...how to modify it?

import java.util.Calendar

ImageView imageView;

Calendar cal = Calendar.getInstance();

cal.setTime(now_date);

imageView = (ImageView)findViewById(R.id.imageView);

if(cal.get(Calendar.DAY_OF_WEEK) == Calendar.MONDAY) {
    imageView.setImageResource(R.drawable.IMAGE1);
} else if(cal.get(Calendar.DAY_OF_WEEK) == Calendar.TUESDAY) {
    imageView.setImageResource(R.drawable.IMAGE2);
}

CodePudding user response：

java.time

The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern Date-Time API^*.

Solution using java.time, the modern Date-Time API: Use ZonedDateTime with the applicable ZoneId and retrieve the required values from it.

Demo:

import java.time.DayOfWeek;
import java.time.Month;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.TextStyle;
import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        // Specify the applicable ZoneId e.g.
        // ZonedDateTime.now(ZoneId.of("Asia/Kolkata"))
        // to get the current date-time in that timezone
        ZonedDateTime now = ZonedDateTime.now();

        DayOfWeek dow = now.getDayOfWeek();
        System.out.println(dow);

        int weekDayNum = dow.getValue();
        System.out.println(weekDayNum);

        String weekDayName = dow.getDisplayName(TextStyle.FULL, Locale.ENGLISH);
        System.out.println(weekDayName);

        int year = now.getYear();
        System.out.println(year);

        Month month = now.getMonth();
        System.out.println(month);

        int monthValue = month.getValue();
        System.out.println(monthValue);

        int dayOfMonth = now.getDayOfMonth();
        System.out.println(dayOfMonth);

        int dayOfYear = now.getDayOfYear();
        System.out.println(dayOfYear);
    }
}

Output:

MONDAY
1
Monday
2021
NOVEMBER
11
1
305

ONLINE DEMO

Learn more about the modern Date-Time API from Trail: Date Time. Check this answer and this answer to learn how to use java.time API with JDBC.

^{* If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8 APIs available through desugaring. Note that Android 8.0 Oreo already provides support for java.time.}

CodePudding user response：

Similar to DAY_OF_WEEK, you can get other fields from Calendar instance.

Please check Java Docs for more details: https://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html

CodePudding user response：

Refer to the documentation https://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html you can get the week, month and year in this way

Date today = new Date(); 
cal.setTime(today); 
int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK); 
int dayOfMonth = cal.get(Calendar.DAY_OF_MONTH);
int dayOfYear = cal.get(Calendar.DAY_OF_YEAR);