Simple way to add different validators to your Android TextView or EditText. Also supports Android's material TextInputLayout and TextInputEditText.
<com.google.android.material.textfield.TextInputLayout
android:id="@+id/text_input_layout"
style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="TextInputLayout"
app:errorEnabled="true"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/icon"
app:layout_constraintTop_toTopOf="parent">
<com.google.android.material.textfield.TextInputEditText
android:id="@+id/text_input_edit"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</com.google.android.material.textfield.TextInputLayout>
<EditText
android:id="@+id/text_edit"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
TextView textInputEdit = findViewById(R.id.text_input_edit);
TextViewValidator validator = new TextViewValidator(textInputEdit)
.addValidator(((view, editable) -> editable.length() > 0 ? null : new ValidationError("Must be greater than 0")))
.addValidator(((view, editable) -> editable.length() < 8 ? null : new ValidationError("Must be smaller than 8")))
.addListener((v, isValid) -> Log.d("Validation changed", Boolean.toString(isValid)));
TextView textView = findViewById(R.id.text_edit);
TextViewValidator validator2 = new TextViewValidator(textView)
.addValidator(((view, editable) -> !"Error".equals(editable) ? null : new ValidationError("Must not be 'Error'")))
.addListener((v, isValid) -> Log.d("Validation changed", Boolean.toString(isValid)));