1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:id="@+id/activity_main"
 4     android:layout_width="match_parent"
 5     android:layout_height="match_parent">
 6 
 7     <EditText
 8         android:id="@+id/edit"
 9         android:layout_width="match_parent"
10         android:layout_height="wrap_content"
11         android:hint="Type something here"/>
12 </LinearLayout>

 1 public class MainActivity extends AppCompatActivity {
 2     private EditText edit;
 3 
 4     @Override
 5     protected void onCreate(Bundle savedInstanceState) {
 6         super.onCreate(savedInstanceState);
 7         setContentView(R.layout.activity_main);
 8         edit=(EditText) findViewById(R.id.edit);
 9         String inputText=load();
10         if(!TextUtils.isEmpty(inputText)){                                 //对字符串进行非空判断
11             edit.setText(inputText);
12             edit.setSelection(inputText.length());
13             Toast.makeText(this,"Restoring succeeded",Toast.LENGTH_SHORT).show();
14         }
15 
16     }
17     @Override
18     protected void onDestroy(){                                           //重写onDestroy()保证在活动销毁之前一定调用这个方法
19         super.onDestroy();
20         String inputText=edit.getText().toString();
21         save(inputText);
22     }
23 
24     public void save(String inputText){
25         FileOutputStream out=null;
26         BufferedWriter writer=null;
27         try{
28             out=openFileOutput("data", Context.MODE_PRIVATE);
29             writer=new BufferedWriter(new OutputStreamWriter(out));
30             writer.write(inputText);
31         }catch(IOException e){
32             e.printStackTrace();
33         }finally{
34             try{
35                 if(writer!=null){
36                     writer.close();
37                 }
38             }catch(IOException e){
39                 e.printStackTrace();
40             }
41         }
42     }
43 
44     public String load(){
45         FileInputStream in=null;
46         BufferedReader reader=null;
47         StringBuilder content=new StringBuilder();
48         try{
49             in=openFileInput("data");
50             reader=new BufferedReader(new InputStreamReader(in));
51             String line="";
52             while((line=reader.readLine())!=null){
53                 content.append(line);
54             }
55         }catch(IOException e){
56             e.printStackTrace();
57         }finally {
58             if(reader!=null){
59                 try{
60                     reader.close();
61                 }catch (IOException e){
62                     e.printStackTrace();
63                 }
64             }
65         }
66         return content.toString();
67     }
68 }