java - Android:如何从类的方法访问值？

Question

看，我有 2 个类可以说是登录类和欢迎类，在登录类中我有全局变量 String Email; 和一个 OnCreate() 。我在该方法中设置了电子邮件的值，现在我的问题是如何获取从方法初始化的变量的值？

public class LoginActivity extends AppCompatActivity {
private EditText email,password;

public String emailText;

protected void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        email = (EditText) findViewById(R.id.email);
        //I want to get this value
        emailText = email.getText().toString();
}
}

我的另一个类(class)是

public class Welcome extends Activity{
protected void onCreate(Bundle savedInstanceState) {
     TextView textView = (TextView) findViewById(R.id.email);
     //this is what I did which is the variable that was unInitialized
     LoginActivity loginActivity = new LoginActivity();
        textView.setText(loginActivity.getEmailText());
}
}

Answer 1

您必须以一些额外的方式开始欢迎 Activity :

    Intent startWelcomeActivityIntent = new Intent(context, Welcome.class);
    startWelcomeActivityIntent.putExtra("keyForUsername", userNameString);
    startWelcomeActivityIntent.putExtra("keyForPassword", passwordString);
    startActivity(startWelcomeActivityIntent);

然后从 Welcome Activity 的 onCreate 方法中检索这个 extras:

protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Intent intentWithData = getIntent();
    String userNameFromLoginActivity = intentWithData.getStringExtra("keyForUsername");
    String passwordFromLoginActivity = intentWithData.getStringExtra("keyForPassword");
}