I am creating a project for my college navigation. I have 13 location points in a closed loop structure as I am working on a single floor (Sixth Floor). I'm taking two inputs from the user as current location and destination and then using A* algorithm to find the shortest path and using images to navigate the user like google street view.
But the problem is that my activity_image_display is totally blank when I run the application and I cannot figure out why
My codes
Main Activity
package com.example.collegeroamer
import android.content.Intent
import android.os.Bundle
import android.widget.ImageButton
import android.widget.Spinner
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
private lateinit var navigateButton: ImageButton
private lateinit var currentLocationSpinner: Spinner
private lateinit var destinationSpinner: Spinner
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
navigateButton = findViewById(R.id.navigateButton)
currentLocationSpinner = findViewById(R.id.currentLocationSpinner)
destinationSpinner = findViewById(R.id.destinationSpinner)
navigateButton.setOnClickListener {
val startingLocation = currentLocationSpinner.selectedItem.toString()
val destination = destinationSpinner.selectedItem.toString()
val intent = Intent(this, NavigationDisplayActivity::class.java)
intent.putExtra("starting_location", startingLocation)
intent.putExtra("destination", destination)
startActivity(intent)
}
}
}
Navigation Display Activity.kt
package com.example.collegeroamer
import android.os.Bundle
import android.widget.ImageView
import androidx.appcompat.app.AppCompatActivity
import kotlinx.coroutines.*
import java.util.*
import kotlin.collections.HashMap
import kotlin.coroutines.CoroutineContext
class NavigationDisplayActivity : AppCompatActivity(), CoroutineScope {
private lateinit var job: Job
override val coroutineContext: CoroutineContext
get() = Dispatchers.Main + job
private lateinit var pathImageView: ImageView
// Map of location points to their corresponding images
private val locationImages = mapOf(
"Class 601" to R.drawable.sixthfloor_class601,
"Class 602" to R.drawable.sixthfloor_class602,
"Class 603" to R.drawable.sixthfloor_class603,
"Class 604" to R.drawable.sixthfloor_class604,
"Class 605" to R.drawable.sixthfloor_class605,
"Class 606" to R.drawable.sixthfloor_class606,
"Class 607" to R.drawable.sixthfloor_class607,
"Class 608" to R.drawable.sixthfloor_class608,
"Class 609" to R.drawable.sixthfloor_class609,
"Class 610" to R.drawable.sixthfloor_class610,
"Class 611" to R.drawable.sixthfloor_class611,
"Class 612" to R.drawable.sixthfloor_class612,
"NSS Unit and DLLE Room" to R.drawable.sixthfloor_nssroom
)
// Map of location points to their connected points
private val adjacencyList = mapOf(
"Class 601" to listOf("Class 602"),
"Class 602" to listOf("Class 601", "Class 603"),
"Class 603" to listOf("Class 602", "Class 604"),
"Class 604" to listOf("Class 603", "Class 605"),
"Class 605" to listOf("Class 604", "Class 606"),
"Class 606" to listOf("Class 605", "NSS Unit and DLLE Room"),
"NSS Unit and DLLE Room" to listOf("Class 606", "Class 607"),
"Class 607" to listOf("NSS Unit and DLLE Room", "Class 608"),
"Class 608" to listOf("Class 607", "Class 609"),
"Class 609" to listOf("Class 608", "Class 610"),
"Class 610" to listOf("Class 609", "Class 611"),
"Class 611" to listOf("Class 610", "Class 612"),
"Class 612" to listOf("Class 611", "Class 601")
)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_image_display)
job = Job()
pathImageView = findViewById(R.id.pathImageView)
// Example usage
val startingLocation = intent.getStringExtra("starting_location") ?: ""
val destination = intent.getStringExtra("destination") ?: ""
launch {
val shortestPath = findShortestPath(startingLocation, destination)
displayPathImages(shortestPath)
}
}
override fun onDestroy() {
super.onDestroy()
job.cancel()
}
private suspend fun findShortestPath(
startingPoint: String,
destinationPoint: String
): List<String> = withContext(Dispatchers.Default) {
val queue = PriorityQueue<Node>()
val visited = mutableSetOf<String>()
val parentMap = HashMap<String, String>()
queue.add(Node(startingPoint, 0))
while (queue.isNotEmpty()) {
val current = queue.poll()
if (current.location == destinationPoint) {
// Found the destination, reconstruct the path
val path = mutableListOf<String>()
var node = current.location
while (node != startingPoint) {
path.add(node)
node = parentMap[node] ?: break
}
path.add(startingPoint)
return@withContext path.reversed()
}
if (current.location !in visited) {
visited.add(current.location)
for (neighbor in adjacencyList[current.location] ?: emptyList()) {
if (neighbor !in visited) {
val cost = current.cost + 1 // Assuming each step has a cost of 1
queue.add(Node(neighbor, cost))
parentMap[neighbor] = current.location
}
}
}
}
return@withContext emptyList()
}
private fun displayPathImages(path: List<String>) {
// Display the images corresponding to the locations in the path
val imageIds = path.map { locationImages[it] ?: 0 }
// Set up your ImageView or other UI elements to display the images
// Example: pathImageView.setImageResource(imageIds.firstOrNull() ?: 0)
}
private data class Node(val location: String, val cost: Int) : Comparable<Node> {
override fun compareTo(other: Node): Int = cost.compareTo(other.cost)
}
}
You current code only have 1 image view pathImageView, and the code for setting image to it is commented in displayPathImages
// Example: pathImageView.setImageResource(imageIds.firstOrNull() ?: 0)
Uncomment the code, better way of doing this can be:
imageIds.firstOrNull()?.let {
pathImageView.setImageResource(it)
}
You current code only show one image, By looking at you code looks like you want to display a list of images, you can use a recycler view for that