android中Fragment的建構函式

最近在使用Fragment的過程中遇到一個問題，初步是想在Fragment中建立一個建構函式，建構函式中傳遞兩個自身需要的變數，如下

public class TestFragment extends Fragment 
{
	private String name;
	private String passwd;
	public TestFragment(String name, String passwd)
	{
		super();
		this.name = name;
		this.passwd = passwd;
	}
	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		View view = inflater.inflate(R.layout.main, null);
		
		return view;
	}

}

結果eclipse報出兩個錯：

This fragment should provide a default constructor (a public constructor with no arguments) (com.example.TestFragment)

Avoid non-default constructors in fragments: use a default constructor plus Fragment#setArguments(Bundle) instead

在增加一個空引數的建構函式可以消去第一個錯誤，但是第二個卻不能，第二個錯誤說要使用預設建構函式外加setArguments(Bundle)來代替，去android的官網上檢視Fragment的例子都是下面這個樣子的

CharSequence mLabel;

    /**
     * Create a new instance of MyFragment that will be initialized
     * with the given arguments.
     */
    static MyFragment newInstance(CharSequence label) {
        MyFragment f = new MyFragment();
        Bundle b = new Bundle();
        b.putCharSequence("label", label);
        f.setArguments(b);
        return f;
    }

既然人家這麼寫例子肯定還是有道理的，我們只需要依葫蘆畫瓢就可以了，去掉帶參的建構函式，建立一個newInstance函式，如下

public class TestFragment extends Fragment 
{
	private String name;
	private String passwd;

	public static TestFragment newInstance(String name, string passwd) {
		TestFragment newFragment = new TestFragment();
		Bundle bundle = new Bundle();
		bundle.putString("name", name);
		bundle.putString("passwd", passwd);
		newFragment.setArguments(bundle);
		return newFragment;

    }
	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		View view = inflater.inflate(R.layout.main, null);
		
		return view;
	}

}

如此這般，第二個錯誤就消失了，在Fragment所依賴的Activity中，用以下語句建立Fragment例項即可

Fragment testFragment=TestFragment.newInstance("name","passwd");

對於從Activity傳遞到Fragment中的引數我們只需要在Fragment的onCreate中獲取就可以了

public void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);

        Bundle args = getArguments();
        if (args != null) {
            name = args.getString("name");
	    passwd = args.getstring("passwd");
        }
}

轉自：http://blog.csdn.net/anobodykey/article/details/22503413