[ Android Studio ] 日期與日期比較大小 - Date與Calendar、GregorianCalendar

一、介紹

Calendar：日曆

GregorianCalendar：陽曆日曆

SimpleDateFormat：簡單日期格式

二、程式語法：

package com.example.date_time;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;

import java.sql.Time;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

public class MainActivity extends AppCompatActivity {

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

        //取得日期時間
        //利用Calendar獲取
        Calendar c = Calendar.getInstance();
        int year = c.get(Calendar.YEAR);//年
        int month = c.get(Calendar.MONTH);//月

        int date= c.get(Calendar.DATE);//日
        int day = c.get(Calendar.DAY_OF_MONTH);//日

        int hour = c.get(Calendar.HOUR_OF_DAY);//小時 , 24小時計算
        int hour2 = c.get(Calendar.HOUR);//小時 ，12小時計算

        int minute = c.get(Calendar.MINUTE);//分鐘
        int second = c.get(Calendar.SECOND);//秒


        Log.i("hour=====>",String.valueOf(hour));
        Log.i("hour2=====>",String.valueOf(hour2));

        //日期轉換成樣式
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss");
        SimpleDateFormat sdf2 = new SimpleDateFormat("HHmmss");
        try {
        //日期轉字串
        Date d = c.getTime();
        String dateString = sdf.format(d);
        Log.i("dateString=====>",dateString);
        //字串轉日期
        String dateString2 = "";
        Date dateParse = sdf.parse(dateString);

        //日期加一小時
        Date d1 = c.getTime();
        c.add(Calendar.HOUR,1);
        String dateString_sum = sdf.format(c.getTime());
        Log.i("目前時間==>",sdf.format(d1)+"加一小時後===>"+dateString_sum);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        //Time獲取
        Time t=new Time(10);

        long gettime = t.getTime(); // 取得系統時間。

        Log.i("gettime=====>",String.valueOf(gettime));
        //=======================比大小
        Calendar c_1 = Calendar.getInstance();
        Calendar c_2 = Calendar.getInstance();
        SimpleDateFormat sdf_1 = new SimpleDateFormat("yyyyMMddHHmmss");
        try {
            c_1.setTime(sdf_1.parse("20200917025920"));
            Date x0 =c_1.getTime();
            Date x1 = c_2.getTime();
            Log.i("結果",x1.compareTo(x0)+"");//  I/結果 ：: 1

        } catch (ParseException e) {
            e.printStackTrace();
        }
        //日期比大小===========================
      
        Calendar cal1 = new GregorianCalendar(2019, 8, 10);
        Calendar cal2 = new GregorianCalendar(2007, 2, 02);

        int i = cal1.compareTo(cal2);

        System.out.println("結果 :"+i);//結果：1

        int j = cal2.compareTo(cal1);

        System.out.println("結果 :" + j);//結果：-1

    }
}