I am building a Count Down Timer app, that starts on pushing the button. The app crashes on pressing the button

Question

On clicking the button the app gets crashed displaying "Unfortunately, zm(app name) has stopped".

The IDE did not show any error.

I tried running this in 2 different devices but it didn't work.

Removing the final keyword shows an error.

ActivityMain.java

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
   @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final TextView timer_text = (TextView) findViewById(R.id.text);
        Button start_button = (Button) findViewById(R.id.button_start);

        start_button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                final CountDownTimer timer = new CountDownTimer(30000,1000) { //setting time for 30 sec
                    @Override
                    public void onTick(long l) {
                        timer_text.setText((int) (l/1000)); //updating by reducing 1 second
                    }
                    @Override
                    public void onFinish() {
                        timer_text.setText(R.string.done); //string that shows completion

                    }
                }.start();

            }
        });
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/text"
        android:layout_width="259dp"
        android:layout_height="83dp"
        android:text="Press the button to start"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.444" />

    <Button
        android:id="@+id/button_start"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="56dp"
        android:text="start"
        app:layout_constraintTop_toBottomOf="@+id/text"
        tools:layout_editor_absoluteX="161dp"
        tools:ignore="MissingConstraints" />

</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

Your problem is a type mismatch.

You are doing:

timer_text.setText((int) (l / 1000));

But that mean that you are actually using the TextView.setText(int resId) method, not the setText(String text) method. Causing it to crash because there is no resource id with your calcul.

A simple solution would be:

timer_text.setText(String.valueOf(l / 1000));

Moreover

• Your code is a bit hard to read, you seems to have pasted multiple time our code.

• You should not be using lower_snake_case as variable name, but lowerCamelCase instead.