实现记住密码

Main2Activity
public class Main2Activity extends AppCompatActivity {
    private SharedPreferences sharedPreferences;
    private SharedPreferences.Editor editor;

    private EditText userEdit;
    private EditText passwordEdit;
    private CheckBox rememberpass;
    private Button login;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        sharedPreferences= PreferenceManager.getDefaultSharedPreferences(this);
        userEdit=(EditText)findViewById(R.id.user);
        passwordEdit=(EditText)findViewById(R.id.password);
        rememberpass=(CheckBox)findViewById(R.id.remember_pass);
        login=(Button)findViewById(R.id.login);


        boolean isRemmber=sharedPreferences.getBoolean("remember_password",false);
        if (isRemmber){
            String user=sharedPreferences.getString("user","");
            String password=sharedPreferences.getString("password","");
//                       Log.i("rrr", "password is: "+password);
            userEdit.setText(user);
            passwordEdit.setText(password);
            rememberpass.setChecked(true);
        }



        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String user=userEdit.getText().toString();
                String password=passwordEdit.getText().toString();
                if(user.equals("wang")&&password.equals("123")){
                    editor=sharedPreferences.edit();
                    if (rememberpass.isChecked()){
                        editor.putBoolean("remember_password",true);
                        editor.putString("user",user);
                        editor.putString("password",password);
                    }else {
                        editor.clear();
                    }
                    Log.d("wang",user+password);
                    editor.apply();

                    Intent intent=new Intent(Main2Activity.this,Main3Activity.class);
                    intent.putExtra("user",user);
                    intent.putExtra("password",password);
                    startActivity(intent);
                }else {
                    Toast.makeText(Main2Activity.this,"user or password is invalid",Toast.LENGTH_SHORT).show();
                }
            }
        });

    }
}

Main3Activity
public class Main3Activity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main3);
        TextView users=(TextView)findViewById(R.id.userl);
        TextView passwords=(TextView)findViewById(R.id.passwordl);
        Intent intent=getIntent();
        String user=intent.getStringExtra("user");
        String password=intent.getStringExtra("password");
        users.setText(user);
        passwords.setText(password);
    }
}

activity_main2.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".Main2Activity">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="60dp">
        <TextView
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:textSize="18sp"
            android:text="User:"/>
        <EditText
            android:id="@+id/user"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_gravity="center_vertical"/>
    </LinearLayout>
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="60dp">
        <TextView
            android:layout_gravity="center_vertical"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:textSize="18sp"
            android:text="Password:"/>
        <EditText
            android:id="@+id/password"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_gravity="center_vertical"
            android:inputType="textPassword"/>
    </LinearLayout>
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <CheckBox
            android:id="@+id/remember_pass"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
        <TextView
            android:textSize="18sp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Remember passworld"/>
    </LinearLayout>
    <Button
        android:id="@+id/login"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:text="Login"/>
</LinearLayout>

activity_main3.xml
LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".Main3Activity">

    <TextView
        android:id="@+id/userl"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="60sp"/>
    <TextView
        android:id="@+id/passwordl"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="60sp"/>
</LinearLayout>