Question

我正在关注一个教程并尝试在我的片段中构建一个网格视图，每次启动应用程序时它都会崩溃。我打开了LogCat并且它什么也没给我......有人可以帮我找出我能做些什么来让它正确显示而不是崩溃的应用程序？谢谢!!!

下面我已经包含了我的主要活动，GridView适配器和片段...

MainActivity

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 ---我觉得问题就在这里，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

我猜你正试图在活动的布局中找到一个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;
}

如果不是问题的原因，请在发生崩溃时发布堆栈跟踪（应该已经完成）。

Answer 2

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

删除getItemId中的GridViewAdapter方法。你无论如何都不能使用它。 BaseAdapter可能正在引用它，并且从该方法返回null可能会使适配器崩溃。

代码建议，返回此方法的项目：

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

Answer 3

LogCat并没有给我什么......

如果没有任何内容，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。因此，在第二行中使用getActivity()而不是使用rootView。

并记得将gridView布局放在inventory_layout

中

Answer 4

我不确定这是否是唯一的问题，但这个看起来有点不对劲。在Inventory_Fragment类中：

gridview.setAdapter(new GridViewAdapter(this));

您应该将其更改为：

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

另请在此处上传您的布局和/或logcat报告。这样的代码很难通过。

添加Gridview以使其崩溃

4 个答案: