How to check programmatically if an application is installed or not in Android?

Try with this:

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Add respective layout
        setContentView(R.layout.main_activity);

        // Use package name which we want to check
        boolean isAppInstalled = appInstalledOrNot("com.check.application");  
        
        if(isAppInstalled) {
            //This intent will help you to launch if the package is already installed
            Intent LaunchIntent = getPackageManager()
                .getLaunchIntentForPackage("com.check.application");
            startActivity(LaunchIntent);
                    
            Log.i("SampleLog", "Application is already installed.");          
        } else {
            // Do whatever we want to do if application not installed
            // For example, Redirect to play store

            Log.i("SampleLog", "Application is not currently installed.");
        }
    }

    private boolean appInstalledOrNot(String uri) {
        PackageManager pm = getPackageManager();
        try {
            pm.getPackageInfo(uri, PackageManager.GET_ACTIVITIES);
            return true;
        } catch (PackageManager.NameNotFoundException e) {
        }

        return false;
    }

}