SharedPreferences保存少量的数据

1.MainActivity.java

public class MainActivity extends AppCompatActivity {    SharedPreferences preferences;    SharedPreferences.Editor editor;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //获取只能被 本程序读写的sharepreferences对象        preferences = getSharedPreferences("crazyit",MODE_PRIVATE);        editor = preferences.edit(); //调用方法edit()来获取editor的对象        Button read = (Button)findViewById(R.id.read);        Button wrtie= (Button)findViewById(R.id.write);        read.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                  //读取字符串数据               String time = preferences.getString("time",null);                //记取int 整数类型的数据                int randNum = preferences.getInt("random",0);                String result = time == null ? "你暂时没有写入时间数据" : "写入时间为：" + time + "上次生成的随机数：" + randNum;                Toast.makeText(MainActivity.this,result,Toast.LENGTH_LONG).show();            }        });        wrtie.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {    /*             SimpleDateFormat sdf =new SimpleDateFormat("yyyy 年 MM 月 dd 日"                                       +  "hh:mm:ss" );*/                java.text.SimpleDateFormat sdf =  new  java.text.SimpleDateFormat("yyyy 年 MM 月 dd 日"                       +  "hh:mm:ss" );                //存入当前的时间                editor.putString("time",sdf.format(new Date()));                //存入随机数                editor.putInt("random",(int)(Math.random()*100));                //提交所有存入的数据                editor.commit();            }        });    }}

2.xml文件

  activity_main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout    android:id="@+id/activity_main"    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.sh.appsharepreferences.MainActivity">    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Hello World!"/>    <Button        android:id="@+id/read"        android:text="read data"        android:layout_width="wrap_content"        android:layout_height="wrap_content"/>    <Button        android:id="@+id/write"        android:text="write data"        android:layout_width="wrap_content"        android:layout_height="wrap_content"/>LinearLayout>

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