Validation: Added Toast messages for empty or invalid input

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

@@ -4,7 +4,9 @@ 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;
@@ -27,53 +29,41 @@ public class MainActivity extends AppCompatActivity {
             return insets;
         });
 
-        TextInputLayout tempInput = findViewById(R.id.inputTemp);
-        Button CtoF = findViewById(R.id.but_cToF);
-        Button FtoC = findViewById(R.id.but_fToC);
+        TextInputLayout tempInput = findViewById(R.id.inputLayoutTemp);
+        RadioButton radCtoF = findViewById(R.id.radBut_CtoF);
+        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) {
-                assert tempInput.getEditText() != null;
+                tempInput.setError(null);
+                if (tempInput.getEditText() == null) return;
                 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 f = c * (9.0/5.0) + 32;
-                    @SuppressLint("DefaultLocale") String resultString = String.format("%.2f °F", f);
-                    result.setText(resultString);
-
-                } catch (NumberFormatException e) {
-                    // Handle cases where the input is not a valid decimal number
-                    tempInput.setError("Invalid number format");
-                }
-            }
-        });
-
-        FtoC.setOnClickListener(new View.OnClickListener(){
-
-            @Override
-            public void onClick(View v) {
-                assert tempInput.getEditText() != null;
-                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);
+                    double inputTemp = Double.parseDouble(userInput);
+                    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 {
+                        // Fahrenheit to Celsius
+                        double c = (5.0/9.0) * (inputTemp - 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();
                 }
             }
         });
@@ -83,6 +73,10 @@ public class MainActivity extends AppCompatActivity {
             @Override
             public void onClick(View v) {
                 result.setText("");
+                if (tempInput.getEditText() != null) {
+                    tempInput.getEditText().setText("");
+                }
+                tempInput.setError(null);
             }
         });
     }

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

@@ -3,97 +3,141 @@
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/main"
-    android:layout_width="wrap_content"
+    android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:textAlignment="center"
     tools:context=".MainActivity">
 
-    <TextView
-        android:id="@+id/result"
-        android:layout_width="109dp"
-        android:layout_height="28dp"
-        android:layout_marginStart="4dp"
-        android:layout_marginTop="28dp"
-        android:textSize="20sp"
-        app:layout_constraintStart_toEndOf="@+id/text_conversion"
-        app:layout_constraintTop_toBottomOf="@+id/inputTemp" />
-
     <TextView
         android:id="@+id/textView2"
-        android:layout_width="410dp"
-        android:layout_height="44dp"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="16dp"
         android:text="Temperature Conversion"
         android:textAlignment="center"
         android:textSize="24sp"
         app:layout_constraintTop_toTopOf="parent"
-        tools:layout_editor_absoluteX="8dp" />
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent" />
 
     <TextView
         android:id="@+id/text_Temp"
-        android:layout_width="128dp"
+        android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_marginStart="8dp"
-        android:layout_marginTop="4dp"
-        android:lineSpacingExtra="10sp"
+        android:layout_marginStart="16dp"
         android:text="Temperature:"
-        android:textAlignment="center"
         android:textSize="20sp"
-        android:typeface="sans"
+        app:layout_constraintBottom_toBottomOf="@+id/inputLayoutTemp"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/textView2" />
+        app:layout_constraintTop_toTopOf="@+id/inputLayoutTemp" />
 
     <com.google.android.material.textfield.TextInputLayout
-        android:layout_width="408dp"
+        android:id="@+id/inputLayoutTemp"
+        android:layout_width="0dp"
         android:layout_height="wrap_content"
+        android:layout_marginStart="8dp"
         android:layout_marginEnd="16dp"
-        app:layout_constraintEnd_toEndOf="parent"
-        tools:layout_editor_absoluteY="44dp">
-
-    </com.google.android.material.textfield.TextInputLayout>
-
-    <com.google.android.material.textfield.TextInputEditText
-        android:id="@+id/inputTemp"
-        android:layout_width="280dp"
-        android:layout_height="41dp"
-        android:hint="Enter Temperature"
+        android:layout_marginTop="16dp"
+        app:hintEnabled="false"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toEndOf="@+id/text_Temp"
-        app:layout_constraintTop_toBottomOf="@+id/textView2" />
+        app:layout_constraintTop_toBottomOf="@+id/textView2">
+
+        <com.google.android.material.textfield.TextInputEditText
+            android:id="@+id/inputTemp"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:hint="Enter Temperature"
+            android:textColorHint="#9E9E9E"
+            android:inputType="numberDecimal|numberSigned" />
+    </com.google.android.material.textfield.TextInputLayout>
 
     <TextView
         android:id="@+id/text_conversion"
-        android:layout_width="109dp"
-        android:layout_height="28dp"
-        android:layout_marginTop="40dp"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="16dp"
+        android:layout_marginTop="24dp"
         android:text="Conversion:"
         android:textSize="20sp"
-        app:layout_constraintTop_toBottomOf="@+id/text_Temp"
-        tools:layout_editor_absoluteX="4dp" />
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/inputLayoutTemp" />
 
-    <Button
-        android:id="@+id/but_cToF"
-        android:layout_width="409dp"
-        android:layout_height="51dp"
+    <TextView
+        android:id="@+id/result"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="8dp"
+        android:layout_marginEnd="16dp"
+        android:textSize="20sp"
+        app:layout_constraintBottom_toBottomOf="@+id/text_conversion"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toEndOf="@+id/text_conversion"
+        app:layout_constraintTop_toTopOf="@+id/text_conversion" />
+
+    <TextView
+        android:id="@+id/txt_select"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="16dp"
         android:layout_marginTop="24dp"
-        android:text="C to F"
-        android:textColorLink="#A09F9F"
-        app:layout_constraintTop_toBottomOf="@+id/text_conversion"
-        tools:layout_editor_absoluteX="34dp" />
+        android:text="Select Conversion:"
+        android:textSize="18sp"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/text_conversion" />
 
-    <Button
-        android:id="@+id/but_fToC"
-        android:layout_width="409dp"
-        android:layout_height="51dp"
-        android:text="F to C"
-        app:layout_constraintTop_toBottomOf="@+id/but_cToF"
-        tools:layout_editor_absoluteX="0dp" />
+    <RadioGroup
+        android:id="@+id/radioGroup"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="16dp"
+        android:layout_marginTop="8dp"
+        app:layout_constraintStart_toStartOf="parent"
+        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="409dp"
-        android:layout_height="51dp"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="16dp"
+        android:layout_marginTop="24dp"
+        android:layout_marginEnd="8dp"
+        android:backgroundTint="#A9A7A7"
         android:text="Reset"
-        app:layout_constraintTop_toBottomOf="@+id/but_fToC"
-        tools:layout_editor_absoluteX="-13dp" />
+        android:textColor="#FFFFFF"
+        app:cornerRadius="0dp"
+        app:layout_constraintEnd_toStartOf="@+id/but_calc"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toStartOf="parent"
+        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>