1 protected void onCreate(Bundle savedInstanceState) {
 2         super.onCreate(savedInstanceState);
 3         requestWindowFeature(Window.FEATURE_NO_TITLE);
 4         setContentView(R.layout.activity_login);
 5         context = this;
 6                 ll_login = (LinearLayout)findViewById(R.id.ll_activity_login);//这里ll_login的值便是null
 7                ll_login.setOnClickListener(new View.OnClickListener(){
 8             @Override
 9             public void onClick(View v) {
10                 switch (v.getId()) {
11                 case R.id.ll_login:
12                      InputMethodManager imm = (InputMethodManager)
13                      getSystemService(Context.INPUT_METHOD_SERVICE);
14                      imm.hideSoftInputFromWindow(v.getWindowToken(), 0);
15                     break;
16                 }
17 
18             }
19         });     
20     }

1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
2     xmlns:tools="http://schemas.android.com/tools"
3     android:id="@+id/ll_activity_login"
4     android:layout_width="match_parent"
5     android:layout_height="match_parent"
6     android:clickable="true"
7     android:background="@color/white_color"
8     android:orientation="vertical" >