<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ChronometerExample"
    android:orientation="vertical"
    android:gravity="center"
    android:padding="16dp">

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="10dp"
        android:text="CHRONOMETER"
        android:textColor="@color/colorOrange"
        android:textSize="20dp"
        android:textStyle="bold" />

    <Button
        android:id="@+id/startButton"
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView1"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="10dp"
        android:text="Start"
        android:textColor="@color/colorWhite"
        android:background="@color/colorAccent" />

    <Button
        android:id="@+id/stopButton"
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:layout_below="@+id/startButton"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="10dp"
        android:text="Stop"
        android:textColor="@color/colorWhite"
        android:background="@color/colorAccent" />

    <Button
        android:id="@+id/restartButton"
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:layout_below="@+id/stopButton"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="10dp"
        android:text="Restart"
        android:textColor="@color/colorWhite"
        android:background="@color/colorAccent" />

    <Button
        android:id="@+id/setFormat"
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:layout_below="@+id/restartButton"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="10dp"
        android:text="Set Format"
        android:textColor="@color/colorWhite"
        android:background="@color/colorAccent" />

    <Button
        android:id="@+id/clearFormat"
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:layout_below="@+id/setFormat"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="10dp"
        android:text="Clear Format"
        android:textColor="@color/colorWhite"
        android:background="@color/colorAccent" />
    <!-- chronometer with black background and red text color -->
    <Chronometer
        android:id="@+id/simpleChronometer"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/clearFormat"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp"
        android:background="@color/colorPrimary"
        android:gravity="center"
        android:padding="10dp"
        android:textColor="@color/colorWhite"
        android:textStyle="bold" />

</LinearLayout>

                                    
                                  

                                    
                                        package com.example.widgets;

import android.os.SystemClock;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Chronometer;

public class ChronometerExample extends AppCompatActivity {

    Chronometer simpleChronometer;
    Button start, stop, restart, setFormat, clearFormat;

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

        simpleChronometer = findViewById(R.id.simpleChronometer);
        start = findViewById(R.id.startButton);
        stop = findViewById(R.id.stopButton);
        restart = findViewById(R.id.restartButton);
        setFormat = findViewById(R.id.setFormat);
        clearFormat = findViewById(R.id.clearFormat);

        // perform click event on start button to start a chronometer
        start.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                simpleChronometer.start();
            }
        });

        // perform click event on stop button to stop the chronometer
        stop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                simpleChronometer.stop();
            }
        });

        // perform click event on restart button to set the base time on chronometer
        restart.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                simpleChronometer.setBase(SystemClock.elapsedRealtime());
            }
        });

        // perform click event on set Format button to set the format of chronometer
        setFormat.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                simpleChronometer.setFormat("Time (%s)");
            }
        });

        // perform click event on clear button to clear the current format of chronometer as you set through set format
        clearFormat.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                simpleChronometer.setFormat(null);
            }
        });
    }
}
                                    
                                  

                                    
                                        package com.example.widgets

import android.os.SystemClock
import android.os.Bundle
import android.view.View
import android.widget.Button
import android.widget.Chronometer
import androidx.appcompat.app.AppCompatActivity

class ChronometerExample : AppCompatActivity() {

    private lateinit var simpleChronometer: Chronometer
    private lateinit var start: Button
    private lateinit var stop: Button
    private lateinit var restart: Button
    private lateinit var setFormat: Button
    private lateinit var clearFormat: Button

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_chronometer_example)

        simpleChronometer = findViewById(R.id.simpleChronometer)
        start = findViewById(R.id.startButton)
        stop = findViewById(R.id.stopButton)
        restart = findViewById(R.id.restartButton)
        setFormat = findViewById(R.id.setFormat)
        clearFormat = findViewById(R.id.clearFormat)

        // perform click event on start button to start a chronometer
        start.setOnClickListener {
            simpleChronometer.start()
        }

        // perform click event on stop button to stop the chronometer
        stop.setOnClickListener {
            simpleChronometer.stop()
        }

        // perform click event on restart button to set the base time on chronometer
        restart.setOnClickListener {
            simpleChronometer.base = SystemClock.elapsedRealtime()
        }

        // perform click event on set Format button to set the format of chronometer
        setFormat.setOnClickListener {
            simpleChronometer.format = "Time (%s)"
        }

        // perform click event on clear button to clear the current format of chronometer as you set through set format
        clearFormat.setOnClickListener {
            simpleChronometer.format = null
        }
    }
}