Check if a app is installed and go to the market if not. We have to pass the package of the app in the param.

_Main.java

PackageUtils.startNewActivity(getApplicationContext(), "com.microsoft.office.lync15");

PackageUtils.java

public class PackageUtils {

    public static void startNewActivity(Context context, String packageName) {
        Intent intent = context.getPackageManager().getLaunchIntentForPackage(packageName);
        if (intent == null) {
            intent = new Intent(Intent.ACTION_VIEW);
            intent.setData(Uri.parse("market://details?id=" + packageName));
        }
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(intent);
    }
}