Android应用中按日期顺序显示字符串数组内容教程

<!-- res/values/strings.xml -->
<resources>
    <string-array name="daily_greetings">
        <item>早安，祝您有美好的一天！</item>
        <item>新的一天，新的开始，加油！</item>
        <item>阳光正好，微风不燥，享受当下。</item>
        <item>保持微笑，每天都是最好的自己。</item>
        <item>祝您今天事事顺利，心情愉悦！</item>
    </string-array>
</resources>

import android.content.res.Resources;

// ...
String[] dailyGreetingsArray;

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

    Resources res = getResources();
    dailyGreetingsArray = res.getStringArray(R.array.daily_greetings);
    // ... 其他初始化
}

import android.content.SharedPreferences;
import android.widget.TextView;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;

public class MainActivity extends AppCompatActivity {

    private static final String PREF_NAME = "DailyGreetingPrefs";
    private static final String KEY_LAST_UPDATE_DAY = "lastUpdateDay";
    private static final String KEY_CURRENT_INDEX = "currentIndex";

    private SharedPreferences sharedPreferences;
    private TextView dailyGreetingTextView;
    private String[] dailyGreetingsArray;

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

        // 初始化视图
        dailyGreetingTextView = findViewById(R.id.dailyGreetingTextView); // 假设您在布局中有一个ID为dailyGreetingTextView的TextView

        // 获取字符串数组
        dailyGreetingsArray = getResources().getStringArray(R.array.daily_greetings);

        // 初始化SharedPreferences
        sharedPreferences = getSharedPreferences(PREF_NAME, MODE_PRIVATE);

        // 调用更新方法
        updateDailyGreeting();
    }

    // ...
}

    private void updateDailyGreeting() {
        if (dailyGreetingsArray == null || dailyGreetingsArray.length == 0) {
            dailyGreetingTextView.setText("暂无每日问候语。");
            return;
        }

        // 获取当前日期
        Calendar calendar = Calendar.getInstance();
        int currentDayOfYear = calendar.get(Calendar.DAY_OF_YEAR); // 获取一年中的第几天
        int currentYear = calendar.get(Calendar.YEAR); // 获取当前年份，用于处理跨年情况

        // 从SharedPreferences获取上次更新的日期和索引
        int lastUpdateDayOfYear = sharedPreferences.getInt(KEY_LAST_UPDATE_DAY, -1);
        int lastUpdateYear = sharedPreferences.getInt("lastUpdateYear", -1); // 存储年份
        int currentIndex = sharedPreferences.getInt(KEY_CURRENT_INDEX, 0); // 默认从第一个开始

        // 检查是否是新的一天或首次运行
        boolean isNewDay = (currentDayOfYear != lastUpdateDayOfYear) || (currentYear != lastUpdateYear);
        boolean isFirstRun = (lastUpdateDayOfYear == -1); // 首次运行判断

        if (isFirstRun || isNewDay) {
            // 如果是首次运行或新的一天，更新索引并保存
            if (!isFirstRun) { // 如果不是首次运行，才需要递增索引
                currentIndex = (currentIndex + 1) % dailyGreetingsArray.length;
            }
            // 更新TextView
            dailyGreetingTextView.setText(dailyGreetingsArray[currentIndex]);

            // 保存新的日期和索引到SharedPreferences
            SharedPreferences.Editor editor = sharedPreferences.edit();
            editor.putInt(KEY_LAST_UPDATE_DAY, currentDayOfYear);
            editor.putInt("lastUpdateYear", currentYear); // 保存年份
            editor.putInt(KEY_CURRENT_INDEX, currentIndex);
            editor.apply(); // 使用apply()异步保存，提高性能
        } else {
            // 如果是同一天，则显示上次保存的问候语
            dailyGreetingTextView.setText(dailyGreetingsArray[currentIndex]);
        }
    }

<!-- res/layout/activity_main.xml -->
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/dailyGreetingTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="每日问候语将显示在这里"
        android:textSize="20sp"
        android:textColor="@android:color/black"
        android:textAlignment="center" />

</RelativeLayout>