Android应用中实现每日轮播字符串数组内容的教程

<!-- res/values/strings.xml -->
<resources>
    <string-array name="daily_greetings">
        <item>早上好！今天又是充满希望的一天。</item>
        <item>美好的一天从此刻开始，祝您心情愉快！</item>
        <item>新的一天，新的开始，愿您一切顺利。</item>
        <item>清晨的阳光，带来新的力量。早安！</item>
        <item>愿您今天的努力，都能开花结果。早安！</item>
    </string-array>
</resources>

import android.content.SharedPreferences;
import android.content.res.Resources;
import android.os.Bundle;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import java.util.Calendar;

public class MainActivity extends AppCompatActivity {

    private static final String PREFS_NAME = "DailyMessagePrefs";
    private static final String KEY_LAST_DAY_OF_YEAR = "lastDayOfYear";
    private static final String KEY_CURRENT_INDEX = "currentIndex";

    private TextView dailyMessageTextView;
    private String[] dailyMessages;
    private SharedPreferences sharedPreferences;

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

        dailyMessageTextView = findViewById(R.id.dailyMessageTextView);

        // 1. 获取字符串数组资源
        Resources res = getResources();
        dailyMessages = res.getStringArray(R.array.daily_greetings);

        // 2. 初始化SharedPreferences
        sharedPreferences = getSharedPreferences(PREFS_NAME, MODE_PRIVATE);

        // 调用逻辑方法
        updateDailyMessage();
    }
    // ... 其他方法
}

// 承接上文的 MainActivity 类

    private void updateDailyMessage() {
        if (dailyMessages == null || dailyMessages.length == 0) {
            dailyMessageTextView.setText("未找到每日消息。");
            return;
        }

        // 获取当前日期信息：一年中的第几天
        Calendar calendar = Calendar.getInstance();
        int currentDayOfYear = calendar.get(Calendar.DAY_OF_YEAR);

        // 从SharedPreferences加载上次记录的日期和索引
        int lastDayOfYear = sharedPreferences.getInt(KEY_LAST_DAY_OF_YEAR, -1);
        int currentIndex = sharedPreferences.getInt(KEY_CURRENT_INDEX, 0);

        // 判断是否为新的一天
        if (currentDayOfYear != lastDayOfYear) {
            // 是新的一天，更新索引
            currentIndex = (currentIndex + 1) % dailyMessages.length;

            // 保存新的日期和索引到SharedPreferences
            SharedPreferences.Editor editor = sharedPreferences.edit();
            editor.putInt(KEY_LAST_DAY_OF_YEAR, currentDayOfYear);
            editor.putInt(KEY_CURRENT_INDEX, currentIndex);
            editor.apply(); // 使用 apply() 异步保存，性能更好
        }

        // 显示每日消息
        dailyMessageTextView.setText(dailyMessages[currentIndex]);
    }
}

<!-- res/layout/activity_main.xml -->
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center"
    android:padding="16dp"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/dailyMessageTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="加载中..."
        android:textSize="20sp"
        android:textColor="@android:color/black"
        android:gravity="center" />

</LinearLayout>