注册登录

MainActivity

package com.example.lenovo.testapp1;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import java.util.Vector;

public class MainActivity extends AppCompatActivity {

    //获取文本框。判断里边信息
    EditText et_usercode;
    EditText et_password;

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

        et_usercode=(EditText)findViewById(R.id.et_usecode);
        et_password=(EditText)findViewById(R.id.et_password);
    }

    //View表示事件的发起者
    public void bt1_on(View v)
    {
        //带返回的打开一个注册界面Activity

        //1-构造意图
        Intent intent=new Intent(this,ZhuCeActivity.class);

        //启动带返回信息的Activity int   请求码：标识请求
        startActivityForResult(intent,1);
    }

    //三个成员变量
    String usercode;
    String username;
    String password;
    //重写处理返回信息的回调方法

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        //处理返回信息

        //1-判断请求码
        if (requestCode==1)
        {
            //2-判断结果码
            if (resultCode==RESULT_OK)
            {
                //接收返回的注册信息
                usercode=data.getStringExtra("code");
                username=data.getStringExtra("name");
                password=data.getStringExtra("mima");

            }
        }
    }
    //登录的按钮
    public void bt4_on(View v)
    {
        //1-取得填写信息

        //2-判断是否正确填写
        String usecode=et_usercode.getText().toString();
        String password1=et_password.getText().toString();

        if (usecode.trim().length()==0||password.trim().length()==0)
        {
            Toast.makeText(MainActivity.this, "用户代码和密码都不能为空", Toast.LENGTH_SHORT).show();
            return;
        }
        //3-判断有没有注册信息
        //1）没有注册信息
        //2）用户信息尚未注册
        if (usercode==null||(usercode!=null&& !usercode.equals(usecode)))
        {
            Toast.makeText(MainActivity.this, "用户未注册", Toast.LENGTH_SHORT).show();
            return;
        }
        //4-判断注册信息与登录信息是否匹配
        if (!password.equals(password1))
        {
            Toast.makeText(MainActivity.this, "密码错误", Toast.LENGTH_SHORT).show();
            return;
        }
        else
        {
            //可以登陆了
            Toast.makeText(MainActivity.this, "验证成功", Toast.LENGTH_SHORT).show();

            //跳转到主界面

            Intent intent=new Intent(this,TextActivity.class);
            //传递数据
            //把数据放到意图里

            intent.putExtra("usercode",usercode);
            intent.putExtra("username",username);

            startActivity(intent);
        }
        finish();//直接退出

    }
}

activity_main

<?xml version="1.0" encoding="utf-8"?>
<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: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.example.lenovo.testapp1.MainActivity"
    android:orientation="vertical">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="用户代码"
        android:id="@+id/et_usecode"/>
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="密码"
        android:inputType="numberPassword"
        android:id="@+id/et_password"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="登录"
            android:onClick="bt4_on"/>
        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="注册"
            android:onClick="bt1_on"/>
    </LinearLayout>
</LinearLayout>

注册

package com.example.lenovo.testapp1;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class ZhuCeActivity extends AppCompatActivity {

    EditText et_usercode;
    EditText et_username;
    EditText et_psssword;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_zhu_ce);

        et_usercode=(EditText)findViewById(R.id.et_usercode);
        et_username=(EditText)findViewById(R.id.et_username);
        et_psssword=(EditText)findViewById(R.id.et_password);
    }
    //View表示事件的发起者
    public void bt3_on(View v)
    {
        //返回注册信息

        //用户代码取得
        String usercode=et_usercode.getText().toString();

        if (usercode==null||usercode.trim().length()==0)
        {
            Toast.makeText(ZhuCeActivity.this,"请正确填写用户代码",Toast.LENGTH_SHORT).show();
                    return;
        }

        String username=et_username.getText().toString();

        if (username==null||username.trim().length()==0)
        {
            Toast.makeText(ZhuCeActivity.this,"请正确填写用户名称",Toast.LENGTH_SHORT).show();
            return;
        }

        String password=et_psssword.getText().toString();

        if (password==null||password.trim().length()==0)
        {
            Toast.makeText(ZhuCeActivity.this,"请正确填写密码",Toast.LENGTH_SHORT).show();
            return;
        }
        Intent intent=new Intent();

        intent.putExtra("code", usercode);
        intent.putExtra("name", username);
        intent.putExtra("mima",password);

        //设置返回信息：1-结果码，2-携带数据的意图
        setResult(RESULT_OK,intent);
        finish();
    }
    public void bt2_on(View v)
    {
        setResult(RESULT_CANCELED,null);//取消
        finish();
    }
}