android检测是否安装了某应用，并启动

if(hasApplication(getBaseContext(), "com.taobao.taobao")){
                            PackageManager packageManager = getBaseContext().getPackageManager();
                            Intent it = packageManager.getLaunchIntentForPackage("com.taobao.taobao");
                            startActivity(it);
                        } else {
                            Toast.makeText(Main2Activity.this, "不存在该应用", Toast.LENGTH_LONG).show();
                        }




public boolean hasApplication(Context context, String packageName){
        PackageManager packageManager = context.getPackageManager();

        //获取系统中安装的应用包的信息
        List<PackageInfo> listPackageInfo = packageManager.getInstalledPackages(0);
        for (int i = 0; i < listPackageInfo.size(); i++) {
            if(listPackageInfo.get(i).packageName.equalsIgnoreCase(packageName)){
                return true;
            }
        }
        return false;

    }

 附android常用app的包名：https://blog.csdn.net/waterinsidewater/article/details/71124569