判断手机是否安装某程序的方法：

判断手机已安装某程序的方法： 
private boolean isAvilible(Context context, String packageName){ 
          final PackageManager packageManager = context.getPackageManager();//获取packagemanager 
          List< packageInfo> pinfo = packageManager.getInstalledPackages(0);//获取所有已安装程序的包信息 
          List<String> pName = new ArrayList<String>();//用于存储所有已安装程序的包名 
         //从pinfo中将包名字逐一取出，压入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);//判断pName中是否有目标程序的包名，有TRUE，没有FALSE 
    }

判断后的逻辑： 
//已安装，打开程序，需传入参数包名："com.skype.android.verizon" 
if(isAvilible(this, "com.skype.android.verizon")){ 
                Intent i = new Intent(); 
                ComponentName cn = new ComponentName("com.skype.android.verizon", 
                        "com.skype.android.verizon.SkypeActivity"); 
                i.setComponent(cn); 
                startActivityForResult(i, RESULT_OK);    
            } 
//未安装，跳转至market下载该程序 
else { 
                Uri uri = Uri.parse("market://details?id=com.skype.android.verizon");//id为包名 
                Intent it = new Intent(Intent.ACTION_VIEW, uri); 
                startActivity(it); 
            }