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Deep Learning for Android Apps

The MainActivity Class

Explore the MainActivity class in an Android app that uses TensorFlow Lite for image classification. Understand how it initializes UI components, loads images, handles user interactions, and integrates the image classifier model to classify selected images and display results.

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The MainActivity class is the main activity of our app that extends the AppCompatActivity class. It overrides the onCreate() method to set up the UI, initializes the UI components, and handles user interactions.

Fields of the MainActivity

The fields of the MainActivity include:

  • A constant field to define the request code for loading an image.

  • A field (Button) to load images from the storage.

  • A field (ImageView) to view the image on the UI.

  • A field (Bitmap) to represent the selected image.

  • A field (of the type ImageClassifier) to perform image classification using a TF Lite model.

  • A field (TextView) to display the classification result.

  • A field (an instance of ActivityResultLauncher) handling the result of picking an image.

The following code defines these fields:

Kotlin
package com.example.horse_human_classify
import android.graphics.Bitmap
import android.graphics.ImageDecoder
import android.graphics.ImageDecoder.ImageInfo
import android.net.Uri
import android.os.Bundle
import android.widget.Button
import android.widget.ImageView
import android.widget.TextView
import androidx.activity.result.contract.ActivityResultContracts
import androidx.appcompat.app.AppCompatActivity
import java.io.IOException
class MainActivity : AppCompatActivity() {
    // Constants for image classifier
    companion object {
        private const val REQUEST_CODE_LOAD_IMAGE = 1
    }
    private lateinit var loadImageButton : Button
    private lateinit var imageView : ImageView
    private lateinit var selectedImage : Bitmap
    private lateinit var classifier : ImageClassifier
    private lateinit var resultTextView : TextView
    // Implement the logic below to pick an image from the device's storage
    //private val pickImage 
    
    
    // Override onCreate() method here
}

  • Lines 18–20: These define a companion object (REQUEST_CODE_LOAD_IMAGE) with a constant property to represent the request code for loading an image. ...