如何根据android应用程序中的日期更改主活动中的图像

Question

寻找一个 android 应用程序，需要日复一日地更改图像。

示例：如果系统日期=01.01.2021，则应显示 image1，否则应显示 image2。

这是我的安卓源代码：

package com.wavedevelopers.chat;

import androidx.appcompat.app.AppCompatActivity;
import java.util.Calendar;
import java.util.Date;

import android.os.Bundle;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {


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

        ImageView imageView;

        Calendar cal = Calendar.getInstance();

        Date now_date = null;
        cal.setTime(now_date);

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

        if(cal.get(Calendar.DAY_OF_WEEK) == Calendar.MONDAY)
        {
            imageView.setImageResource(R.drawable.a1);
        }
        else if(cal.get(Calendar.DAY_OF_WEEK) == Calendar.TUESDAY)
        {
            imageView.setImageResource(R.drawable.a2);
        }


    }
}

Answer 1

    package com.wavedevelopers.chat;

import androidx.appcompat.app.AppCompatActivity;
import java.util.Calendar;
import java.util.Date;

import android.os.Bundle;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {


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

        ImageView imageView;

        Calendar cal = Calendar.getInstance();
        int dayOfMonth = cal.get(Calendar.DAY_OF_MONTH);

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

        if(cal.get(Calendar.DAY_OF_WEEK) == Calendar.MONDAY && cal.get(Calendar.MONTH) == Calendar.NOVEMBER)
        {
            imageView.setImageResource(R.drawable.a1);
        }
        else if(cal.get(Calendar.DAY_OF_WEEK) == Calendar.TUESDAY)
        {
            imageView.setImageResource(R.drawable.a2);
        }
        else if(dayOfMonth == 1) {
            System.out.println("It's the first of the month")
        }

    }
}