如何为Android的10个Activity实现ViewPager式剩余页面填充指示器？

Got it, since you're dealing with multiple Activities instead of a ViewPager with Fragments, the key here is to track completion state across all Activities and render a custom indicator in each one. Here's a step-by-step solution that mimics the ViewPager indicator style:

1. Create a Global Completion Tracker #

First, you need a way to share completion state between all 10 Activities. A singleton class works great for real-time updates, and we can add persistence if you need to retain state after app restarts.

object ActivityCompletionTracker {
    private val completedActivities = BooleanArray(10) { false }

    // Mark an activity as completed (pass its index: 0-9)
    fun markActivityCompleted(position: Int) {
        if (position in 0..9) {
            completedActivities[position] = true
        }
    }

    // Check if an activity is completed
    fun isActivityCompleted(position: Int): Boolean {
        return position in 0..9 && completedActivities[position]
    }

    // Get total completed activities
    fun getCompletedCount(): Int {
        return completedActivities.count { it }
    }

    // Optional: Persist state to SharedPreferences
    fun saveState(context: Context) {
        val prefs = context.getSharedPreferences("ActivityCompletion", Context.MODE_PRIVATE)
        val editor = prefs.edit()
        completedActivities.forEachIndexed { index, isCompleted ->
            editor.putBoolean("activity_$index", isCompleted)
        }
        editor.apply()
    }

    // Optional: Load saved state on app start
    fun loadState(context: Context) {
        val prefs = context.getSharedPreferences("ActivityCompletion", Context.MODE_PRIVATE)
        for (index in 0..9) {
            completedActivities[index] = prefs.getBoolean("activity_$index", false)
        }
    }
}

2. Add Indicator Layout to Each Activity #

In every Activity's layout XML, add a container for the indicator dots (and optional text for remaining count):

<!-- Add this to your Activity layout, e.g., at the top or bottom -->
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:gravity="center"
    android:padding="16dp">

    <TextView
        android:id="@+id/tv_remaining"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="还剩10个页面需要填写"
        android:layout_marginBottom="8dp"/>

    <LinearLayout
        android:id="@+id/ll_indicator_container"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"/>
</LinearLayout>

3. Create Indicator Dot Drawables #

Make 3 drawable resources to represent different states:

indicator_dot_current.xml (Current Activity's dot) #

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval">
    <solid android:color="@color/primary"/> <!-- Use your app's primary color -->
</shape>

indicator_dot_completed.xml (Completed Activity's dot) #

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval">
    <solid android:color="@color/grey_700"/>
</shape>

indicator_dot_incomplete.xml (Unfinished Activity's dot) #

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval">
    <stroke android:color="@color/grey_300" android:width="2dp"/>
    <solid android:color="@android:color/transparent"/>
</shape>

4. Implement Indicator Rendering in Each Activity #

Add this method to every Activity to build and update the indicator. Call it in onResume() to ensure it refreshes when the Activity comes back into view:

private fun setupIndicator(currentActivityIndex: Int) {
    val indicatorContainer = findViewById<LinearLayout>(R.id.ll_indicator_container)
    val remainingText = findViewById<TextView>(R.id.tv_remaining)

    // Update remaining count text
    val remaining = 10 - ActivityCompletionTracker.getCompletedCount()
    remainingText.text = "还剩$remaining 个页面需要填写"

    // Clear existing dots before rebuilding
    indicatorContainer.removeAllViews()

    val dotSize = resources.getDimensionPixelSize(R.dimen.indicator_dot_size)
    val dotMargin = resources.getDimensionPixelSize(R.dimen.indicator_dot_margin)

    // Create a dot for each Activity
    for (index in 0..9) {
        val dot = View(this)
        val params = LinearLayout.LayoutParams(dotSize, dotSize)
        params.setMargins(dotMargin, 0, dotMargin, 0)
        dot.layoutParams = params

        // Set dot background based on state
        dot.setBackgroundResource(
            when {
                index == currentActivityIndex -> R.drawable.indicator_dot_current
                ActivityCompletionTracker.isActivityCompleted(index) -> R.drawable.indicator_dot_completed
                else -> R.drawable.indicator_dot_incomplete
            }
        )

        indicatorContainer.addView(dot)
    }
}

// Call this in onResume
override fun onResume() {
    super.onResume()
    setupIndicator(0) // Replace 0 with this Activity's index (0-9)
}

Don't forget to add the dimensions to res/values/dimens.xml:

<dimen name="indicator_dot_size">16dp</dimen>
<dimen name="indicator_dot_margin">8dp</dimen>

5. Update Completion State When User Finishes an Activity #

When the user completes the current Activity's form, mark it as done and save the state (if using persistence):

// Example: On submit button click
btn_submit.setOnClickListener {
    // Mark current Activity as completed (use its index)
    ActivityCompletionTracker.markActivityCompleted(0)
    // Optional: Save state to persist across app restarts
    ActivityCompletionTracker.saveState(this)
    
    // Navigate to next Activity
    startActivity(Intent(this, NextActivity::class.java))
}

6. Initialize Persistence (Optional) #

If you want to retain completion state after the app closes, add this to your custom Application class:

class MyApp : Application() {
    override fun onCreate() {
        super.onCreate()
        ActivityCompletionTracker.loadState(this)
    }
}

And register the Application class in AndroidManifest.xml:

<application
    android:name=".MyApp"
    ...>
    ...
</application>

内容的提问来源于stack exchange，提问作者Mehdi