带数据的activity跳转

public class MainActivity extends Activity {
  TextView tv;
  EditText et;
  Button bt;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  tv = (TextView)findViewById(R.id.tv);
  et = (EditText)findViewById(R.id.et);
  bt = (Button)findViewById(R.id.bt);

bt.setOnClickListener(new OnClickListener() {

@Override
  public void onClick(View arg0) {
    Intent intent = new Intent(MainActivity.this,SecondActivity.class);
    if(et.getText().length()>0)     //如果et存在数据
      {
        Bundle bundle = new Bundle();          //定义bundle
        bundle.putString("username", et.getText().toString());     //将et饿的数据放入bundle
        intent.putExtras(bundle);       //将bundle放入intent
      }
      startActivity(intent);   //启动项目activity
    }
   });
  }
}

public class SecondActivity extends Activity {
  TextView tv;
  Button bt;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);
    tv = (TextView)findViewById(R.id.tv);

Intent intent = getIntent();    //接收穿来的activity数据
    Bundle bundle = intent.getExtras();   //接收穿来的intent里的bundle
    String username = bundle.getString("username").toString();    //定义username
    tv.setText("unername: " + username);   //tv输出内容
  }
}

若有不足之处，欢迎指出。