Validation: Added Toast messages for empty or invalid input

app/src/main/java/com/example/assignmentone/MainActivity.java

@@ -1,16 +1,12 @@
-/*
-Assignment 1 (part1)
-Assignment_1
-Lew Price
-*/
-
 package com.example.assignmentone;
 
 import android.annotation.SuppressLint;
 import android.os.Bundle;
 import android.view.View;
 import android.widget.Button;
+import android.widget.RadioButton;
 import android.widget.TextView;
+import android.widget.Toast;
 
 import androidx.activity.EdgeToEdge;
 import androidx.appcompat.app.AppCompatActivity;
@@ -34,12 +30,12 @@ public class MainActivity extends AppCompatActivity {
         });
 
         TextInputLayout tempInput = findViewById(R.id.inputLayoutTemp);
-        Button CtoF = findViewById(R.id.but_cToF);
+        RadioButton radCtoF = findViewById(R.id.radBut_CtoF);
-        Button FtoC = findViewById(R.id.but_fToC);
+        Button calculate = findViewById(R.id.but_calc);
         Button reset = findViewById(R.id.but_reset);
         TextView result = findViewById(R.id.result);
 
-        CtoF.setOnClickListener(new View.OnClickListener(){
+        calculate.setOnClickListener(new View.OnClickListener(){
 
             @Override
             public void onClick(View v) {
@@ -48,39 +44,26 @@ public class MainActivity extends AppCompatActivity {
                 String userInput = tempInput.getEditText().getText().toString().trim();
                 if(userInput.isEmpty()) {
                     tempInput.setError("Please enter a temperature");
+                    Toast.makeText(MainActivity.this, "Error: No value entered", Toast.LENGTH_SHORT).show();
                     return;
                 }
                 try {
-                    double c = Double.parseDouble(userInput);
+                    double inputTemp = Double.parseDouble(userInput);
-                    double f = c * (9.0/5.0) + 32;
+                    if (radCtoF.isChecked()) {
+                        // Celsius to Fahrenheit
+                        double f = inputTemp * (9.0/5.0) + 32;
                         @SuppressLint("DefaultLocale") String resultString = String.format("%.2f °F", f);
                         result.setText(resultString);
-
+                    } else {
-                } catch (NumberFormatException e) {
+                        // Fahrenheit to Celsius
-                    tempInput.setError("Invalid number format");
+                        double c = (5.0/9.0) * (inputTemp - 32);
-                }
-            }
-        });
-
-        FtoC.setOnClickListener(new View.OnClickListener(){
-
-            @Override
-            public void onClick(View v) {
-                tempInput.setError(null);
-                if (tempInput.getEditText() == null) return;
-                String userInput = tempInput.getEditText().getText().toString().trim();
-                if(userInput.isEmpty()) {
-                    tempInput.setError("Please enter a temperature");
-                    return;
-                }
-                try {
-                    double f = Double.parseDouble(userInput);
-                    double c = (5.0/9.0)*(f-32);
                         @SuppressLint("DefaultLocale") String resultString = String.format("%.2f °C", c);
                         result.setText(resultString);
+                    }
 
                 } catch (NumberFormatException e) {
                     tempInput.setError("Invalid number format");
+                    Toast.makeText(MainActivity.this, "Error: Invalid number or special characters", Toast.LENGTH_SHORT).show();
                 }
             }
         });

app/src/main/res/layout/activity_main.xml

@@ -74,49 +74,70 @@
         app:layout_constraintStart_toEndOf="@+id/text_conversion"
         app:layout_constraintTop_toTopOf="@+id/text_conversion" />
 
-    <Button
+    <TextView
-        android:id="@+id/but_cToF"
+        android:id="@+id/txt_select"
-        android:layout_width="0dp"
+        android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginStart="16dp"
         android:layout_marginTop="24dp"
-        android:layout_marginEnd="16dp"
+        android:text="Select Conversion:"
-        android:backgroundTint="#A9A7A7"
+        android:textSize="18sp"
-        android:text="C to F"
-        android:textColor="#FFFFFF"
-        app:cornerRadius="0dp"
-        app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@+id/text_conversion" />
 
-    <Button
+    <RadioGroup
-        android:id="@+id/but_fToC"
+        android:id="@+id/radioGroup"
-        android:layout_width="0dp"
+        android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginStart="16dp"
-        android:layout_marginEnd="16dp"
         android:layout_marginTop="8dp"
-        android:backgroundTint="#A9A7A7"
-        android:text="F to C"
-        android:textColor="#FFFFFF"
-        app:cornerRadius="0dp"
-        app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/but_cToF" />
+        app:layout_constraintTop_toBottomOf="@+id/txt_select">
+
+        <RadioButton
+            android:id="@+id/radBut_CtoF"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="C to F"
+            android:checked="true" />
+
+        <RadioButton
+            android:id="@+id/radBut_FtoC"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="F to C" />
+    </RadioGroup>
 
     <Button
         android:id="@+id/but_reset"
         android:layout_width="0dp"
         android:layout_height="wrap_content"
         android:layout_marginStart="16dp"
-        android:layout_marginEnd="16dp"
+        android:layout_marginTop="24dp"
-        android:layout_marginTop="8dp"
+        android:layout_marginEnd="8dp"
         android:backgroundTint="#A9A7A7"
         android:text="Reset"
         android:textColor="#FFFFFF"
         app:cornerRadius="0dp"
-        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintEnd_toStartOf="@+id/but_calc"
+        app:layout_constraintHorizontal_bias="0.5"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/but_fToC" />
+        app:layout_constraintTop_toBottomOf="@+id/radioGroup" />
+
+    <Button
+        android:id="@+id/but_calc"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="8dp"
+        android:layout_marginTop="24dp"
+        android:layout_marginEnd="16dp"
+        android:backgroundTint="#A9A7A7"
+        android:text="Calculate"
+        android:textColor="#FFFFFF"
+        app:cornerRadius="0dp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toEndOf="@+id/but_reset"
+        app:layout_constraintTop_toBottomOf="@+id/radioGroup" />
 
 </androidx.constraintlayout.widget.ConstraintLayout>