The code in Android runs a simple method specifying Apk

Sometimes, when we write our own applications, we need to code the specified apk, install the specified theme, or install the new apk. This can be done by:

private void installAPK(String apkUrl) {  
  Intent intent = new Intent(Intent.ACTION_VIEW);  
  intent.setDataAndType(Uri.parse("file://" + apkUrl),  
    "application/vnd.android.package-archive");  
  startActivity(intent);//  The installation   
 }  

apkUrl refers to the path of the application, and Intent is used to open Apk for installation.