activity_main.xml

<LinearLayout 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" >

 

<EditText

android:id="@+id/userName"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:hint="Please input your username" />

 

<EditText

android:id="@+id/passWord"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:hint="Please input your password"

android:inputType="textPassword" />

 

<Button

android:id="@+id/btn_login"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="login"

android:textSize="30sp" />

 

</LinearLayout>

activity_second.xml

<LinearLayout 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" >

 

<TextView

android:id="@+id/info"

android:layout_width="wrap_content"

android:layout_height="wrap_content" />

 

<Button

android:id="@+id/btn_showinfo"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="showIfo" />

 

</LinearLayout>

MainActivity.java

package com.example.testsharedpreferencesdemo001;

 

import android.annotation.SuppressLint;

import android.app.Activity;

import android.content.Intent;

import android.content.SharedPreferences;

import android.content.SharedPreferences.Editor;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

 

public class MainActivity extends Activity

{

 

SharedPreferences sharedPreferences;

Editor editor;

EditText userName, passWord;

Button login;

 

@SuppressLint("CommitPrefEdits")

@Override

protected void onCreate(Bundle savedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

userName = (EditText) findViewById(R.id.userName);

passWord = (EditText) findViewById(R.id.passWord);

 

login = (Button) findViewById(R.id.btn_login);

login.setOnClickListener(myOnClickListener);

 

sharedPreferences = this.getSharedPreferences("login_info",

MODE_PRIVATE);

 

String stored_username = sharedPreferences.getString("username", "");

String stored_password = sharedPreferences.getString("password", "");

userName.setText(stored_username);

passWord.setText(stored_password);

editor = sharedPreferences.edit();

editor.putString("username", userName.getText().toString());

editor.putString("password", passWord.getText().toString());

 

}

 

OnClickListener myOnClickListener = new OnClickListener()

{

 

@Override

public void onClick(View v)

{

String sUserName = userName.getText().toString();

String sPassWord = passWord.getText().toString();

 

Intent intent = new Intent(MainActivity.this, SecondActivity.class);

intent.putExtra("username", sUserName);

intent.putExtra("password", sPassWord);

 

startActivity(intent);

 

}

};

}

SecondActivity.java

package com.example.testsharedpreferencesdemo001;

 

import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.TextView;

import android.widget.Toast;

 

public class SecondActivity extends Activity

{

String userName;

String passWord;

TextView info;

Button btn_showInfo;

 

@Override

protected void onCreate(Bundle savedInstanceState)

{

 

super.onCreate(savedInstanceState);

this.setContentView(R.layout.activity_second);

 

info = (TextView) findViewById(R.id.info);

btn_showInfo = (Button) findViewById(R.id.btn_showinfo);

btn_showInfo.setOnClickListener(new OnClickListener()

{

 

@Override

public void onClick(View v)

{

Toast.makeText(SecondActivity.this, userName + ";" + passWord,

Toast.LENGTH_LONG).show();

}

});

Intent intent = this.getIntent();

userName = intent.getStringExtra("username");

passWord = intent.getStringExtra("password");

System.out.println(userName);

System.out.println(passWord);

 

}

 

}

MainActivity

点击按钮，跳转到SecondActivty，再次点击按钮showinfo

点击“返回键”

回到MainAcitivy

可以看到用户名与密码均保留着