在 Android 中将 Intent 转换为 Fragment

Question

一般来说，我大部分时间都使用 Intent 而不是 Fragment，因为我发现它有点复杂。我有一个带有 ListView 的类来显示数组中的一些数据，我想在 Fragment 中转换它，还想在新的碎片类中传递额外内容。

ListView 类：

public class MainActivity extends Activity {
    ListView list;
    String[] web = { "Google", "Twitter", "Windows", "Bing", "Itunes",
            "Wordpress", "Drupal" };
    Integer[] imageId = { R.drawable.ic_launcher, R.drawable.ic_launcher,
            R.drawable.ic_launcher, R.drawable.ic_launcher,
            R.drawable.ic_launcher, R.drawable.ic_launcher,
            R.drawable.ic_launcher

    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        CustomList adapter = new CustomList(MainActivity.this, web, imageId);
        list = (ListView) findViewById(R.id.list);
        list.setAdapter(adapter);
        list.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                Toast.makeText(MainActivity.this,
                        "You Clicked at " + web[+position], Toast.LENGTH_SHORT)
                        .show();


                Intent i = new Intent(MainActivity.this, intent.class);
                i.putExtra("name", web[+position]);
                startActivity(i);

            }
        });

    }

}

自定义列表类：

public class CustomList extends ArrayAdapter<String> {

    private final Activity context;
    private final String[] web;
    private final Integer[] imageId;

    public CustomList(Activity context, String[] web, Integer[] imageId) {
        super(context, R.layout.list_single, web);
        this.context = context;
        this.web = web;
        this.imageId = imageId;

    }

    @Override
    public View getView(int position, View view, ViewGroup parent) {
        LayoutInflater inflater = context.getLayoutInflater();
        View rowView = inflater.inflate(R.layout.list_single, null, true);
        TextView txtTitle = (TextView) rowView.findViewById(R.id.txt);

        ImageView imageView = (ImageView) rowView.findViewById(R.id.img);
        txtTitle.setText(web[position]);

        imageView.setImageResource(imageId[position]);
        return rowView;
    }
}

我有一个主类，其中包含三个使用片段创建的选项卡，我想在这个类中添加 ListView！

public class LayoutOne extends Fragment {


    public static Fragment newInstance(Context context) {
        LayoutOne f = new LayoutOne();  

        return f;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
        ViewGroup root = (ViewGroup) inflater.inflate(R.layout.layout_one, null);
        return root;

    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

    }

}

我想做的是在片段类中显示列表视图，当单击列表项时，我想启动新意图以显示单击了哪个项！

Answer 1

如果您想将参数传递到 Fragment，通常的做法是创建一个静态方法，该方法会生成具有某些参数的 Fragment 实例。您已经有了newInstance 方法，现在您只需向参数添加参数并返回Fragment。您应该检查onCreateView 中的参数。以下是您如何编写参数的示例。

public class LayoutOne extends Fragment 
{

    public static Fragment newInstance(int someInt, String someString) 
    {
        LayoutOne f = new LayoutOne();

        Bundle args = new Bundle();
        args.putInt("someInt", someInt);
        args.putString("someString", someString);
        f.setArguments(args);

        return f;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) 
    {
        ViewGroup root = (ViewGroup) inflater.inflate(R.layout.layout_one, null);
        Bundle args = getArguments();

        //From here you would check to see if your arguments are present 
        //proceed accordingly

        return root;

    }
}

对于您的具体情况，您可以传递字符串数组并将其添加为参数。

希望这会有所帮助。祝你好运！

编辑

您面临的问题是您在 Activity 中实例化了 ListView，而实际上您应该在 Fragment 中进行实例化。这里不需要意图，您只需要确保有一个ListView 属性可以从您附加到Fragment 的布局中获取。下面是一个小例子，说明它应该如何工作。

注意，这个方法在你的 LayoutOne 类中

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) 
{
    ViewGroup root = (ViewGroup) inflater.inflate(R.layout.layout_one, null);

    //Be sure to use the actual id of your list view
    ListView lv = (ListView) root.findViewById(R.id.list_view_id);

    //Make sure that you retrieve the values for 'web' and 'imageId' from 
    //the activity using the "newInstance" method.
    CustomList adapter = new CustomList(getActivity(), web, imageId);
    lv.setAdapter(adapter);

    //From here, set your onClickListener and stuff as you did in your Activity

    return root;

}

请注意，Fragments 没有 findViewById 方法。您必须在要膨胀的 View 上调用它以作为其布局，因此在这种情况下，您膨胀了 root，然后您将调用 root.findViewById(R.id.some_id) 以获取视图。