用Android studio java语言实现一个简洁的登陆注册界面的类似功能，登录的信息用文本记录，登录页面填写手机号、密码，左下角是一个注册按钮，右下角是登录按钮，点击登录后显示已成功登录即可；点击注册按钮则跳转到注册页面，注册页面可填写姓名、手机号、密码，底下为注册按钮，填写完资料后点击注册即可完成注册，可进行登录操作。

好的，下面是一个简单的登陆注册界面实现的示例代码（仅供参考）：

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private EditText mPhoneEditText;
    private EditText mPasswordEditText;

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

        mPhoneEditText = findViewById(R.id.phone_edit_text);
        mPasswordEditText = findViewById(R.id.password_edit_text);

        Button loginButton = findViewById(R.id.login_button);
        loginButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String phone = mPhoneEditText.getText().toString();
                String password = mPasswordEditText.getText().toString();

                // 判断手机号和密码是否为空
                if (TextUtils.isEmpty(phone) || TextUtils.isEmpty(password)) {
                    Toast.makeText(MainActivity.this, "手机号或密码不能为空", Toast.LENGTH_SHORT).show();
                    return;
                }

                // 判断手机号和密码是否匹配
                if (checkLoginInfo(phone, password)) {
                    Toast.makeText(MainActivity.this, "登录成功", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(MainActivity.this, "手机号或密码错误", Toast.LENGTH_SHORT).show();
                }
            }
        });

        Button registerButton = findViewById(R.id.register_button);
        registerButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, RegisterActivity.class);
                startActivity(intent);
            }
        });
    }

    // 检查手机号和密码是否匹配
    private boolean checkLoginInfo(String phone, String password) {
        String info = readFile("login.txt");
        if (TextUtils.isEmpty(info)) {
            return false;
        }

        String[] infos = info.split(",");
        if (infos.length != 2) {
            return false;
        }

        String savedPhone = infos[0];
        String savedPassword = infos[1];

        return phone.equals(savedPhone) && password.equals(savedPassword);
    }

    // 读取文件
    private String readFile(String fileName) {
        try {
            FileInputStream fis = openFileInput(fileName);
            byte[] buffer = new byte[1024];
            int len = -1;
            StringBuilder sb = new StringBuilder();
            while ((len = fis.read(buffer)) != -1) {
                sb.append(new String(buffer, 0, len));
            }
            fis.close();
            return sb.toString();
        } catch (IOException e) {
            e.printStackTrace();
            return "";
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/phone_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="手机号"/>

    <EditText
        android:id="@+id/password_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="密码"
        android:inputType="textPassword"/>

    <Button
        android:id="@+id/login_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="登录"/>

    <Button
        android:id="@+id/register_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="注册"
        android:layout_marginTop="16dp"/>

</LinearLayout>

RegisterActivity.java

public class RegisterActivity extends AppCompatActivity {
    private EditText mNameEditText;
    private EditText mPhoneEditText;
    private EditText mPasswordEditText;

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

        mNameEditText = findViewById(R.id.name_edit_text);
        mPhoneEditText = findViewById(R.id.phone_edit_text);
        mPasswordEditText = findViewById(R.id.password_edit_text);

        Button registerButton = findViewById(R.id.register_button);
        registerButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = mNameEditText.getText().toString();
                String phone = mPhoneEditText.getText().toString();
                String password = mPasswordEditText.getText().toString();

                // 判断姓名、手机号和密码是否为空
                if (TextUtils.isEmpty(name) || TextUtils.isEmpty(phone) || TextUtils.isEmpty(password)) {
                    Toast.makeText(RegisterActivity.this, "姓名、手机号或密码不能为空", Toast.LENGTH_SHORT).show();
                    return;
                }

                // 保存注册信息
                if (saveRegisterInfo(name, phone, password)) {
                    Toast.makeText(RegisterActivity.this, "注册成功", Toast.LENGTH_SHORT).show();
                    finish();
                } else {
                    Toast.makeText(RegisterActivity.this, "注册失败", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

    // 保存注册信息
    private boolean saveRegisterInfo(String name, String phone, String password) {
        try {
            FileOutputStream fos = openFileOutput("login.txt", MODE_PRIVATE);
            String info = phone + "," + password;
            fos.write(info.getBytes());
            fos.close();
            return true;
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
    }
}

activity_register.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/name_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="姓名"/>

    <EditText
        android:id="@+id/phone_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="手机号"/>

    <EditText
        android:id="@+id/password_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="密码"
        android:inputType="textPassword"/>

    <Button
        android:id="@+id/register_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="注册"
        android:layout_marginTop="16dp"/>

</LinearLayout>

这个示例代码只是实现了最基本的功能，还有很多需要优化和改进的地方，比如密码加密、手机号格式验证、登录状态保持等等。