how to your send WhatsApp message from android using intent

 MainActivity.java

import android.content.Intent;

import android.content.pm.PackageManager;

import android.net.Uri;

import android.os.Bundle;

import android.view.Gravity;

import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        // open whatsapp through intent

        openWhatsApp("+919865426582");

    }

    private void openWhatsApp(String contactNumber) {

        String url = "https://api.whatsapp.com/send?phone=" + contactNumber;

        Intent intent = new Intent(Intent.ACTION_VIEW);

        intent.setData(Uri.parse(url));

        intent.setPackage("com.whatsapp");

        startActivity(intent);

    }

}