安卓判斷是否安裝應用，沒安裝從應用商店下載安裝

public static boolean isAvilible(Context context, String packageName){ 
        final PackageManager packageManager = context.getPackageManager();//獲取packagemanager 
        List< PackageInfo> pinfo = packageManager.getInstalledPackages(0);//獲取全部已安裝程序的包信息 
        List<String> pName = new ArrayList<String>();//用於存儲全部已安裝程序的包名 
       //從pinfo中將包名字逐一取出，壓入pName list中 
            if(pinfo != null){ 
            for(int i = 0; i < pinfo.size(); i++){ 
                String pn = pinfo.get(i).packageName; 
                pName.add(pn); 
            } 
        } 
        return pName.contains(packageName);//判斷pName中是否有目標程序的包名，有TRUE，沒有FALSE 
  } 

if(BaiduTool.isAvilible(Setting_activity.this.getApplicationContext(), "com.baidu.BaiduMap")){ 
                try {
                    intent = Intent.getIntent("intent://map/direction?origin=latlng:"+BaiduTool.getInstance().getLocationX()+","+BaiduTool.getInstance().getLocationY()+"|name:個人位置&destination= &mode=transit&region=青島&src=移動醫療護理#Intent;scheme=bdapp;package=com.baidu.BaiduMap;end");
                } catch (URISyntaxException e) {
                    ToastUtils.show(getApplicationContext(), "調用百度地圖失敗.");
                    Log.i("BaiduToolisAvilible", "未安裝");
                }
                startActivity(intent);    
            } 
            //未安裝，跳轉至market下載該程序 
            else { 
                //未安裝百度地圖,跳轉應用商店.
                ToastUtils.show(getApplicationContext(), "未安裝百度地圖,跳轉應用商店.");
                Uri uri = Uri.parse("market://details?id=com.baidu.BaiduMap");//id爲包名 
                Intent it = new Intent(Intent.ACTION_VIEW, uri); 
                startActivity(it); 
            }
            //移動APP調起Android百度地圖方式舉例