intent（1、传递参数）

//发送
intent.putExtra("key1", "value1");
intent.putExtra("key2", 2.0f);

//接受
Intent intent  = this.getIntent();
String value1  = intent.getStringExtra("key1");
float  value2   = intent.getFloatExtra("key2",0);

public class User implements Serializable { //也可以是parcelable，类似

//发送
Bundle bundle = new Bundle();
                    
User user = new User();
user.setUsername("fredric");
user.setPassword("sinny");
bundle.putSerializable("user", user);
intent.putExtras(bundle);   

//接收
Intent intent = this.getIntent();
Bundle bundle = intent.getExtras();
        
User user = (User) bundle.get("user");     

//发送
List<User> userlist = new ArrayList<User>();
for(int i = 0; i < 10; i++){
    User tmp = new User();
    tmp.setUsername("sinny");
    tmp.setPassword("fredric" + i);
    userlist.add(tmp);
}
                    
intent.putExtra("userlist", (Serializable)userlist);

//接收
List<User> userlist = (List<User>)intent.getSerializableExtra("userlist");
        
Iterator<User> iterator = userlist.iterator();
        
while(iterator.hasNext()){
    User tmp = iterator.next();
    Log.i(TAG_ACTIVITY, tmp.getUsername() + tmp.getPassword());
}