forme

package com.example.app0811.mytodo;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity
{
    SharedPreferences myPref;
    SharedPreferences.Editor editor;

    private EditText userName;
    private EditText passWord;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setPoints();
    }

    private void setPoints()
    {
        myPref = getApplicationContext().getSharedPreferences(Register.myPrefs,MODE_PRIVATE);
        editor =myPref.edit();

        userName = (EditText)findViewById(R.id.inUser);
        passWord = (EditText)findViewById(R.id.inPass);
    }

    private void chkUser()
    {
        String userInput = userName.getText().toString();
        String passInput = passWord.getText().toString();

        if(userInput.trim().equals("") || passInput.trim().equals(""))
        {
            Toast.makeText(this,"Error, please fill all the fields",Toast.LENGTH_SHORT).show();
        }
        else if(!myPref.contains(userInput) || !passInput.equals(myPref.getString(userInput,passInput)))
        {
            Toast.makeText(this,"Error, wrong username or password!",Toast.LENGTH_SHORT).show();
        }
        else
        {
            Intent logMe = new Intent(this,Logged.class);
            this.startActivity(logMe);
        }
    }

}
=========================================================================================================================
=============================register

package com.example.app0811.mytodo;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

/**
 * Created by app0811 on 16/03/2016.
 */
public class Register extends Activity
{
    public final static String myPrefs = "myPref";//shared prefrences xml file name

    SharedPreferences myPref;
    SharedPreferences.Editor editor;

    private EditText userInput;
    private EditText passInput;
    private EditText rePassInput;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);
        setPoints();
    }

    private void setPoints()
    {
        myPref = getApplicationContext().getSharedPreferences(myPrefs,MODE_PRIVATE);
        editor =myPref.edit();

        userInput = (EditText)findViewById(R.id.setUser);
        passInput = (EditText)findViewById(R.id.setPass);
        rePassInput = (EditText)findViewById(R.id.confPass);
    }

    private void chkReg()
    {
        String userName = userInput.getText().toString();
        String passWord = passInput.getText().toString();
        String checkPass = rePassInput.getText().toString();

        if(userName.trim().length()<=0 || passWord.trim().length()<=0 || checkPass.trim().length()<=0)
        {
            Toast.makeText(this, "Error, please fill all the fields", Toast.LENGTH_SHORT).show();
        }
        else if(!checkPass.equals(passWord))
        {
            Toast.makeText(this, "Error, Password do not match!", Toast.LENGTH_SHORT).show();
        }
        else if(userName.equals(myPref.contains(userName)))
        {
            Toast.makeText(this, "Error, this user allready exists", Toast.LENGTH_SHORT).show();
        }
        else
        {
            editor.putString(userName, passWord);
            editor.commit();

            Intent mainInt = new Intent(this,MainActivity.class);
            this.startActivity(mainInt);
            finish();
        }
    }

    public void btnReg(View v)
    {
        chkReg();
    }

    public void btnCncle(View v)
    {
        Intent cnclInten = new Intent (this,MainActivity.class);
        this.startActivity(cnclInten);
        finish();
    }
}
==============================================================================================
====================================logged

package com.example.app0811.mytodo;

import android.app.Activity;
import android.os.Bundle;

/**
 * Created by app0811 on 16/03/2016.
 */
public class Logged extends Activity
{
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_logged);
    }

}