Andriod:一个Activity向另一个Activity传递数据

intent = new Intent(ActivityA.this,ActivityB.class);
startActivity(intent);

多了一行   绑定数据
intent = new Intent(ActivityA.this,ActivityB.class);
intent.putExtra("data","我是A");
startActivity(intent);

 String sData = getIntent().getStringExtra("data").toString();

Intent intent = new Intent(munemainActivity.this,itemdetailActivity.class); //设置Intent
main_name = (EditText)findViewById(R.id.main_name_in);//获取要传递的信息
String s = main_name.getText().toString(); 
intent.putExtra("usrname",s); //传递信息
startActivity(intent);

String sData = getIntent().getStringExtra("usrname").toString();
usrname = (TextView)findViewById(R.id.itemdetail_usrname_in);
usrname.setText(sData);