Stopwatch app not working?

[Mike Gosling]

I apologize if there's already a thread with this or similar problem I'm currently facing. I just couldn't find it.

I'm trying to simulate simple Stopwatch app, from Head First Android Development book.

I am not sure why I'm getting info that app has stopped working.

Here is the activity code:

package com.hfad.stopwatch;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.os.Handler;
import android.widget.TextView;


public class StopwatchActivity extends AppCompatActivity {
    private int seconds = 0;
    private boolean running;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_stopwatch);
        runTimer();
    }

    //Start the stopwatch running when the Start button is clicked.
    public void onClickStart(View view) {
        running = true;
    }
    //Stop the stopwatch running when the Stop button is clicked.
    public void onClickStop(View view) {
        running = false;
    }

    //Reset the stopwatch when the Reset button is clicked.
    public void onClickReset(View view) {
        running = false;
        seconds = 0;
    }

    private void runTimer() {
        final TextView timeView = (TextView)findViewById(R.id.time_view);
        final Handler handler = new Handler();

        handler.post(new Runnable() {
            @Override
            public void run() {
                int hours = seconds/3600;
                int minutes = (seconds%3600)/60;
                int secs = seconds%60;
                String time = String.format("%d:%02d:%02d",
                        hours, minutes, secs);
                timeView.setText(time);
                if (running) {
                    seconds++;
                }
                handler.postDelayed(this, 1000);
            }
        });

    }



}

And here is layout code:

<?xml version="1.0" encoding="utf-8"?>
<android.widget.RelativeLayout
    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"
    android:paddingBottom="16dp"
    android:paddingLeft="16dp"
    android:paddingRight="16dp"
    android:paddingTop="16dp"
    tools:context=".StopwatchActivity">

    <TextView
        android:id="@+id/text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="0dp"
        android:text=""
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:textSize="92sp"

    />

    <Button
        android:id="@+id/start_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/time_view"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp"
        android:onClick="onClickStart"
        android:text="@string/start"
    />

    <Button
        android:id="@+id/stop_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/start_button"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="30dp"
        android:onClick="onClickStop"
        android:text="@string/stop"
    />

    <Button
        android:id="@+id/reset_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/stop_button"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="40dp"
        android:onClick="onClickReset"
        android:text="@string/reset"
    />

</android.widget.RelativeLayout>

Everything is the same as in the book, but I keep getting "App has stopped working".

[Randy Tong]

Check the log and paste the stacktrace here.

[Mike Gosling]

Do you mean Event Log? I'm new to Android Studio, so everything is mixed up right now

Here is what I got from Event Log:

1:05 AM	Gradle sync started with single-variant sync

1:06 AM	Project setup started

1:06 AM	Source generation ended in 657 ms

1:06 AM	Gradle sync finished in 26 s 806 ms

1:06 AM	NDK Resolution Outcome: Project settings: Gradle model version=5.4.1, NDK version is UNKNOWN

2:12 AM	Executing tasks: [:app:assembleDebug] in project C:\Users\Miljan\AndroidStudioProjects\Stopwatch

2:13 AM	Gradle build finished in 19 s 970 ms

2:13 AM	Install successfully finished in 4 s 201 ms.

2:13 AM	Emulator: Process finished with exit code 0

2:17 AM	Executing tasks: [:app:assembleDebug] in project C:\Users\Miljan\AndroidStudioProjects\Stopwatch

2:17 AM	Gradle build finished in 3 s 33 ms

[Tim Moores]

No, the logcat where messages from the device (or emulator) appear. Not sure how that might be named in Android Studio, though.

[Mike Gosling]

Damn, my bad! In activity I referenced TextView component with an id "time_view", while that same component has in xml file id of "text_view".