如果应用程序已安装在android中，如何发出警报答案

【问题标题】：how to give alert if the app is already installed in android如果应用程序已安装在android中，如何发出警报
【发布时间】：2012-03-21 08:24:30
【问题描述】：

如果应用程序已经安装在android中如何发出警报，如果没有如何提供到android market的链接？？？
我在这里试过

在 For 循环中我需要退出

  public void onClick(View v) 
    { 
          final PackageManager pm = getPackageManager();
           //here i get set of installed apps
         List<ApplicationInfo> packages = pm.getInstalledApplications(PackageManager.GET_META_DATA);

      for (ApplicationInfo packageInfo : packages) 
       {
            //how do i check for installed package with clicked package

          String data=packageInfo.packageName;

          if(data.equals("com.bb"))
          {
            String TAG ="MyActivity";
            Log.d(TAG, "Installed package :" + packageInfo.packageName);
            Log.d(TAG, "Launch Activity :" + pm.getLaunchIntentForPackage(packageInfo.packageName)); 
            Toast.makeText(Listing.this, "You have Installed this Package:com.bb" , Toast.LENGTH_SHORT).show();  

          }

                //if the package is not installed, do this

                  else 
          {


            String dictionary=items[position];
            Toast.makeText(Listing.this, dictionary , Toast.LENGTH_SHORT).show();


            if(dictionary.equalsIgnoreCase("Acronyms"))
            {
                String dictionary2="MAcronyms";
                Intent intent = new Intent(Intent.ACTION_VIEW);
                intent.setData(Uri.parse("https://play.google.com/store/apps/details?id=com." + dictionary2));
                startActivity(intent);
             }
                    }
              }   
             }

问题是如果条件失败，则循环仍在运行（例如，它进入 else 块的 55 次）

【问题讨论】：

标签： android android-layout android-intent android-emulator android-widget

【解决方案1】：

尝试clean->build，然后下面的代码-

public void onClick(View v) 
{ 
    final PackageManager pm = getPackageManager();
    //here i get set of installed apps
    List<ApplicationInfo> packages = pm.getInstalledApplications(PackageManager.GET_META_DATA);

    for (ApplicationInfo packageInfo : packages) 
    {
        //how do i check for installed package with clicked package

        String data=packageInfo.packageName;

        if(data.equals("com.bb"))
        {
            String TAG ="MyActivity";
            Log.d(TAG, "Installed package :" + packageInfo.packageName);
            Log.d(TAG, "Launch Activity :" + pm.getLaunchIntentForPackage(packageInfo.packageName)); 
            Toast.makeText(Listing.this, "You have Installed this Package:com.bb" , Toast.LENGTH_SHORT).show();  
            break;
        }else{//if the package is not installed, do this


            String dictionary=items[position];
            Toast.makeText(Listing.this, dictionary , Toast.LENGTH_SHORT).show();


            if(dictionary.equalsIgnoreCase("Acronyms"))
            {
                String dictionary2="MAcronyms";
                Intent intent = new Intent(Intent.ACTION_VIEW);
                intent.setData(Uri.parse("https://play.google.com/store/apps/details?id=com." + dictionary2));
                startActivity(intent);
            }
        }
    }   
}

【讨论】：

是的，我这样做了，但是，否则循环开始运行 55 次，伙计
什么？你确定吗？现在请清理构建。并尝试更新的答案。或者直接复制粘贴。
包将包含 55 个包名...查看 for 循环它将运行 55 次，因此 else 循环执行..
看，这些是java基础。如果“if”中的条件为假，则每次进入 for 循环时都会触发 else。顺便说一句，if 和 else 不是循环。你可能会说他们阻止了。
是的，我知道...现在如何检查和迭代循环朋友

【解决方案2】：

     public void onClick(View v) 
      {

     String str = "aaa";

     if(package1(str)==1)
     {
         Toast.makeText(Listing.this, "You have Installed this Package:aaa" , Toast.LENGTH_SHORT).show();
     }
     else
     {
            String dictionary2="bba";
            Intent intent = new Intent(Intent.ACTION_VIEW);
            intent.setData(Uri.parse("https://play.google.com/store/apps/details?id=com." + dictionary2));
            startActivity(intent);
     }

  }

     }

public int package1(String str)
{
      int i=0;

      final PackageManager pm = getPackageManager();
        //get a list of installed apps.
      List<ApplicationInfo> packages = pm.getInstalledApplications(PackageManager.GET_META_DATA);

      for (ApplicationInfo packageInfo : packages) 
       {

          String data=packageInfo.packageName;
          if(data.equals(str))
          {
            i=1;

           }
                else
                    {
                   //i=0;

                     }

                 }
                 return i;

              }

【讨论】：