gridview中 intent传数据问题
代码如下：
主函数中
gridview.setOnItemClickListener(new OnItemClickListener() {

public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
HashMap item = (HashMap)parent.getItemAtPosition(position);
Intent intent = new Intent(MainActivity.this, ActivityCardPage.class);

User user = new User();
user._id = Integer.parseInt(String.valueOf(item.get("_id")));
user.username = String.valueOf(item.get("username"));
user.imageId = Integer.parseInt(String.valueOf(item.get("imageid")));
intent.putExtra("user", user);

startActivity(intent);
}

});

ActivityCardPage.java中
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.card_detail);

//获得意图
Intent intent = getIntent();
//从意图中得到需要的user对象
user = (User) intent.getSerializableExtra("user");
// 加载数据,往控件上赋值
loadUserData();
}
public void loadUserData() {
et_name = (TextView) findViewById(R.id.username);

// 为控件赋值
et_name.setText(user.username);
imageView.setImageResource(user.imageId);
}

点击主界面跳转时，程序会意外停止，不知道什么原因，请高手知道，非常感谢