如何在Activity之间传递数据

public class MainActivity extends Activity {

    private EditText et_login_name;
    private EditText et_login_pwd;
    private Button btn_login_register;
    private Button btn_login_login; 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setViews();
        setListener();
    }

    private void setListener() {
        btn_login_register.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, RegisterActivity.class);
                int requestCode = 100;
                startActivityForResult(intent, requestCode);//启动activity
            }
        });                                                                     
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {//当从RegisterActivity发送数据时，会触发此事件
        if(requestCode == 100 && resultCode == this.RESULT_OK){
            String name = data.getStringExtra("name");
            String pwd = data.getStringExtra("pwd");
            et_login_name.setText(name);
            et_login_pwd.setText(pwd);
        }
        super.onActivityResult(requestCode, resultCode, data);
    }
    
    private void setViews() {
        et_login_name =(EditText) findViewById(R.id.et_login_name);
        et_login_pwd =(EditText) findViewById(R.id.et_login_pwd);
        btn_login_register = (Button)findViewById(R.id.btn_login_register);
        btn_login_login = (Button)findViewById(R.id.btn_login_login);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

public class RegisterActivity extends Activity {

    private EditText et_register_name;
    private EditText et_register_pwd;
    private Button btn_register_register;

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

    private void setViews() {
        et_register_name = (EditText)findViewById(R.id.et_register_name);
        et_register_pwd = (EditText)findViewById(R.id.et_register_pwd);
        btn_register_register = (Button)findViewById(R.id.btn_register_register);
    }

    private void setListener() {
        btn_register_register.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                try{
                String name = et_register_name.getText().toString();
                String pwd = et_register_pwd.getText().toString();
                Toast.makeText(RegisterActivity.this, "注册成功", Toast.LENGTH_LONG).show();
                
                Intent data = new Intent();
                data.putExtra("name", name);
                data.putExtra("pwd", pwd);
                RegisterActivity.this.setResult(RegisterActivity.this.RESULT_OK, data);//向MainActivity传送数据
                RegisterActivity.this.finish();
                }catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
        
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.register, menu);
        return true;
    }

}