判断：

private boolean isAppInstalled(Context context,String packagename)
    {
        final PackageManager packageManager = context.getPackageManager();
        List<PackageInfo> pinfo = packageManager.getInstalledPackages(0);
        List<String> pName = new ArrayList<String>();
        if (pinfo != null) {
            for (int i = 0; i < pinfo.size(); i++) {
                String pn = pinfo.get(i).packageName;
                pName.add(pn);
            }
        }
        return pName.contains(packagename);
    }

打开：

Intent resolveIntent = context.getPackageManager()
                            .getLaunchIntentForPackage(PackageName);
context.startActivity(resolveIntent);