Question

是否有任何特定的实例我必须在Toast.makeText（）方法的上下文参数中使用getApplicationcontext（）或this

 Toast.makeText(this, "HI", Toast.LENGTH_LONG).show();

 Toast.makeText(getApplicationcontext(), "HI", Toast.LENGTH_LONG).show();

Answer 1

getApplicationContext ：

根据Developer documention : getApplicationContext

Return the context of the single, global Application object of the current process. This generally should only be used if you need a Context whose lifecycle is separate from the current context, that is tied to the lifetime of the process rather than the current component.

使用：

You can use throughout your application with the help of getting Application context using

public class YourApp extends Application
{
 static YourApp appstate;
 public void onCreate(Bundle savedInstanceState){
    super.onCreate();
    appstate = this;
   }
 public static YourApp getApplication(){
    return appstate;
   }
}

如何使用它：YourApp.getApplication();

的此的

Within an instance method or a constructor, this is a reference to the current object.

使用：You can use as along as you can see your Activity Context

e.g。

public void onCreate(Bundled savedInstanceState) { ... Toast.makeText(this, "HI", Toast.LENGTH_LONG).show(); }

如何使用this来区分getApplicationContext()和Toast.makeText()的使用？

尝试使用AynscTask和this在getApplicationContext中使用Toast.makeText（）。

Answer 2

您可以关注

View.getContext(): Returns the context the view is currently running in. Usually the currently active Activity.

Activity.getApplicationContext(): Returns the context for the entire application (the process all the Activities are running inside of). Use this instead of the current Activity context if you need a context tied to the lifecycle of the entire application, not just the current Activity.

＆＃34;这＆＃34;和getContext（）都是相同的

[参考] [getContext（），getApplicationContext（），getBaseContext（）和“this”之间的区别[] 1

使用getApplicationcontext（）和amp;这在Toast .maketext（）方法中

2 个答案: