Timer example

package com.example.timecounter;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    TextView tvTimer;
    Handler handler;
    Runnable runnable;
    int seconds;
    int start;
    int end;
    int step;


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

        tvTimer = findViewById(R.id.tvTimer);
        // count up
        start = 0;
        end = 10;
        step = 1;

        // count down
        //start=10;
        //end =0;
        //step=-1;


        seconds = start;
        tvTimer.setText(seconds + "");

        handler = new Handler();
        runnable = new Runnable() {
            @Override
            public void run() {
                makeStep();

                if (step > 0) {
                    // counting up
                    if (seconds >= end) {
                        Toast.makeText(MainActivity.this, "Time Over", Toast.LENGTH_SHORT).show();
                    } else
                        handler.postDelayed(runnable, 1000);
                } else {
                    // counting down
                    if (seconds <= end) {
                        Toast.makeText(MainActivity.this, "Time Over", Toast.LENGTH_SHORT).show();
                    } else
                        handler.postDelayed(runnable, 1000);
                }
            }
        };
        handler.postDelayed(runnable, 1000);

    }

    public void makeStep() {
        seconds = seconds + step;
        tvTimer.setText(seconds + "");
    }
}