传递参数后打开新的 activity

Question

有人可以帮助我吗？我如何在传递基本登录参数后打开一个新的 activity，这是我的代码，我不知道发生了什么，我收到一个错误：

public class MainActivity extends AppCompatActivity {

    EditText usern = (EditText)findViewById(R.id.user_name);
    String user_name = usern.getText().toString();
    EditText passw = (EditText)findViewById(R.id.password);
    String pass_word = passw.getText().toString();

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

    /** Called when the user clicks the Send button */
    public void nextPage(View view) {
        // Do something in response to button
        if (user_name.equals("sheldonmad") && pass_word.equals("password")) {
            Intent intent = new Intent(this, SecondActivity.class);
            startActivity(intent);
        }
    }
}

Answer 1

@Sheldon Madison：试试这个方法。需要对全局或局部变量进行适当的初始化。请阅读官方文档 http://developer.android.com/intl/es/index.html

public class MainActivity extends AppCompatActivity {

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

        /** Called when the user clicks the Send button */
        public void nextPage(View view) {

        EditText usern = (EditText)findViewById(R.id.user_name);
        String user_name = usern.getText().toString();
        EditText passw = (EditText)findViewById(R.id.password);
        String pass_word = passw.getText().toString();
            // Do something in response to button
            if (user_name.equals("sheldonmad") && pass_word.equals("password")) {
                Intent intent = new Intent(this, SecondActivity.class);
                startActivity(intent);
            }
        }
    }

Answer 2

尝试

     public class MainActivity extends AppCompatActivity {
     EditText usern,passw;
     String user_name,pass_word;

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

                usern = (EditText)findViewById(R.id.user_name);                    
                passw = (EditText)findViewById(R.id.password);                  
                }

                /** Called when the user clicks the Send button */
                public void nextPage(View view) {

    user_name = usern.getText().toString();
  pass_word = passw.getText().toString();
                    // Do something in response to button
                    if (user_name.equals("sheldonmad") && pass_word.equals("password")) {
                        Intent intent = new Intent(this, SecondActivity.class);
                        startActivity(intent);
                    }
                }
            }

传递参数后打开新的 activity

Open new activity after passing argument

android

arguments

login

android-activity