android studio登录界面代码

以下是一个简单的Android Studio登录界面代码示例：

activity_main.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical"
    android:padding="16dp">

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

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

    <Button
        android:id="@+id/btn_login"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Login" />

</LinearLayout>

MainActivity.java：

public class MainActivity extends AppCompatActivity {

    private EditText etUsername, etPassword;
    private Button btnLogin;

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

        etUsername = findViewById(R.id.et_username);
        etPassword = findViewById(R.id.et_password);
        btnLogin = findViewById(R.id.btn_login);

        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String username = etUsername.getText().toString().trim();
                String password = etPassword.getText().toString().trim();

                if (TextUtils.isEmpty(username)) {
                    etUsername.setError("Please enter username");
                    return;
                }

                if (TextUtils.isEmpty(password)) {
                    etPassword.setError("Please enter password");
                    return;
                }

                // TODO: Implement login logic here
            }
        });
    }
}