将 Gridview 添加到片段它正在崩溃

Question

我正在学习教程并尝试在我的片段中构建网格视图，但每次我启动该应用程序时它都会崩溃。我打开 LogCat 但它什么也没给我...有人能帮我看看我能做些什么来让它正确显示而不会使应用程序崩溃吗？谢谢！！！

下面我包含了我的 Main Activity、GridView Adapter 和 Fragment...

主要Activity

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;


   import android.view.ViewGroup;


public class MainActivity extends ActionBarActivity
        implements NavigationDrawerFragment.NavigationDrawerCallbacks {

    /**
     * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
     */
    private NavigationDrawerFragment mNavigationDrawerFragment;

    /**
     * Used to store the last screen title. For use in {@link #restoreActionBar()}.
     */
    private Char

Sequence mTitle;

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

    mNavigationDrawerFragment = (NavigationDrawerFragment)
            getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);

    // Set the first title
    mTitle = "Inventory";

    // Set up the drawer.
    mNavigationDrawerFragment.setUp(
            R.id.navigation_drawer,
            (DrawerLayout) findViewById(R.id.drawer_layout));

    // Remove shadow under actionbar
    getSupportActionBar().setElevation(0);
}

@Override
public void onNavigationDrawerItemSelected(int position) {

    Fragment objFragment = null;

    switch (position) {
        case 0:
            objFragment = new Inventory_Fragment();
            mTitle = getString(R.string.title_section1);
            break;
        case 1:
            objFragment = new Orders_Fragment();
            mTitle = getString(R.string.title_section2);
            break;
        case 2:
            objFragment = new Cart_Fragment();
            mTitle = getString(R.string.title_section3);
            break;
        case 3:
            objFragment = new Settings_Fragment();
            mTitle = getString(R.string.title_section4);
            break;
    }


    // update the main content by replacing fragments
    FragmentManager fragmentManager = getSupportFragmentManager();
    fragmentManager.beginTransaction()
            .replace(R.id.container, objFragment)
            .commit();
}

public void onSectionAttached(int number) {
    switch (number) {
        case 1:
            mTitle = getString(R.string.title_section1);
            break;
        case 2:
            mTitle = getString(R.string.title_section2);
            break;
        case 3:
            mTitle = getString(R.string.title_section3);
            break;
        case 4:
            mTitle = getString(R.string.title_section4);
            break;
    }
}

public void restoreActionBar() {
    ActionBar actionBar = getSupportActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
    actionBar.setDisplayShowTitleEnabled(true);
    actionBar.setTitle(mTitle);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    if (!mNavigationDrawerFragment.isDrawerOpen()) {
        // Only show items in the action bar relevant to this screen
        // if the drawer is not showing. Otherwise, let the drawer
        // decide what to show in the action bar.
        getMenuInflater().inflate(R.menu.main, menu);
        restoreActionBar();
        return true;
    }
    return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    return super.onOptionsItemSelected(item);
}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {
    /**
     * The fragment argument representing the section number for this
     * fragment.
     */
    private static final String ARG_SECTION_NUMBER = "section_number";

    /**
     * Returns a new instance of this fragment for the given section
     * number.
     */
    public static PlaceholderFragment newInstance(int sectionNumber) {
        PlaceholderFragment fragment = new PlaceholderFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        fragment.setArguments(args);
        return fragment;
    }

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.inventory_layout, container, false);
        return rootView;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        ((MainActivity) activity).onSectionAttached(
                getArguments().getInt(ARG_SECTION_NUMBER));
    }
}

// MARK: - Helpers
public void setActionBarTitle(String title) {
    getSupportActionBar().setTitle(title);
}

}

GridViewAdapter

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;

/**
 * Created by kenbarlow on 5/20/15.
 */
public class GridViewAdapter extends BaseAdapter {
    private Context context;

    public GridViewAdapter(Context context) {
        context = context;
    }

    private int[] icons = {
            // Temporary
        R.drawable.image1,
        R.drawable.image2,
        R.drawable.image3,
        R.drawable.image4,
        R.drawable.image5,
        R.drawable.image6,
        R.drawable.image7,
        R.drawable.image8,
        R.drawable.image9,
        R.drawable.image10,
        R.drawable.image11,
        R.drawable.image12,
        R.drawable.image13,
        R.drawable.image14,
        R.drawable.image15,
        R.drawable.image16,
        R.drawable.image17

};


@Override
public int getCount() {
    return icons.length;
}

@Override
public Object getItem(int position){
    return null;
}

@Override
public long getItemId(int position) {
    return 0;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ImageView imageView;
    if (convertView == null) {
        imageView = new ImageView(context);
        imageView.setLayoutParams(new GridView.LayoutParams(100, 100));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setPadding(10, 10, 10, 10);
    } else {
        imageView = (ImageView) convertView;
    }
    imageView.setImageResource(icons[position]);
    return imageView;
}
}

Inventory_Fragment --- 我觉得问题出在这里，但我不确定。

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.GridView;

/**
 * Created by kenbarlow on 5/19/15.
 */
public class Inventory_Fragment extends Fragment {

    View rootView;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        rootView = inflater.inflate(R.layout.inventory_layout, container, false);

    GridView gridview = (GridView) getActivity().findViewById(R.id.gridview);
    gridview.setAdapter(new GridViewAdapter(this));


    return rootView;
}

}

Answer 1

我还没有查看所有代码。我查看了 GridViewAdapter 和 Inventory_Fragment.

删除 GridViewAdapter 中的 getItemId 方法。反正你不用。 BaseAdapter 可能正在引用它，并且 return 从该方法中将其设置为 null 可能会使适配器崩溃。

代码建议，return此方法的一项：

@Override
public Object getItem(int position){
    return icons[position];
}

Answer 2

我猜你正试图在 activity 的布局中找到 gridview，这是错误的，因为 gridview 在 Fragment 的布局中。请更改您的片段代码：

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    rootView = inflater.inflate(R.layout.inventory_layout, container, false);

    GridView gridview = (GridView) rootView.findViewById(R.id.gridview);
    if(gridview != null){
        gridview.setAdapter(new GridViewAdapter(getActivity()));
    }

    return rootView;
}

如果这不是问题的原因，请 post 崩溃发生时的堆栈跟踪（应该已经完成）。

Answer 3

LogCat and it gives me nothing...

如果真的什么都没有，请尝试重置 LogCat。

正如我在这些行中看到的那样

rootView = inflater.inflate(R.layout.inventory_layout, container, false);

GridView gridview = (GridView) getActivity().findViewById(R.id.gridview);

你正在膨胀并使 rootView 找到你的内部布局。所以在第二行使用你的 rootView 而不是 getActivity()。

并记得将 gridView 布局放在 inventory_layout

内

Answer 4

我不确定这是否是唯一的问题，但这一个看起来有点不对。在你的 Inventory_Fragment class:

gridview.setAdapter(new GridViewAdapter(this));

你应该改成这样：

gridview.setAdapter(new GridViewAdapter(getActivity()));

另请上传您的布局and/or logcat 报告在这里。很难通过这样的代码。

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