Question

我相信我的问题是将xml视图与我的活动正确连接。我认为simple_list_item_1.xml是Android用来命名布局的默认方式，但也许我错了...

我一直在关注这个教程，现在我的代码中没有错误，应用程序在我的手机上运行（整体说明很棒，但它的布局很大程度上取决于想象力）：

https://guides.codepath.com/android/Loading-Contacts-with-Content-Providers#using-cursorloader-to-query-the-contentprovider

但是当我运行我的应用程序时，它看起来像这样：

在设计模式中，item_contact.xml如下所示：

我发布了相关文件的确切项目代码。任何帮助，我将非常感激（这可能与问题有关 - 我的应用程序底部的灰色矩形更浅的阴影？）

MainActivity.java：

package com.example.chris.contactswithcursorloader;

import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.database.Cursor;
import android.provider.ContactsContract;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;


public class MainActivity extends AppCompatActivity {
    // ... existing code ...
    private SimpleCursorAdapter adapter;

    // Defines the asynchronous callback for the contacts data loader
    private LoaderManager.LoaderCallbacks<Cursor> contactsLoader =
            new LoaderManager.LoaderCallbacks<Cursor>() {
                // Create and return the actual cursor loader for the contacts data
                @Override
                public Loader<Cursor> onCreateLoader(int id, Bundle args) {
                    // Define the columns to retrieve
                    String[] projectionFields = new String[]{ContactsContract.Contacts._ID,
                            ContactsContract.Contacts.DISPLAY_NAME,
                            ContactsContract.Contacts.PHOTO_URI};
                    // Construct the loader
                    CursorLoader cursorLoader = new CursorLoader(MainActivity.this,
                            ContactsContract.Contacts.CONTENT_URI, // URI
                            projectionFields, // projection fields
                            null, // the selection criteria
                            null, // the selection args
                            null // the sort order
                    );
                    // Return the loader for use
                    return cursorLoader;
                }

                // When the system finishes retrieving the Cursor through the CursorLoader,
                // a call to the onLoadFinished() method takes place.
                @Override
                public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
                    // The swapCursor() method assigns the new Cursor to the adapter
                    adapter.swapCursor(cursor);
                }

                // This method is triggered when the loader is being reset
                // and the loader data is no longer available. Called if the data
                // in the provider changes and the Cursor becomes stale.
                @Override
                public void onLoaderReset(Loader<Cursor> loader) {
                    // Clear the Cursor we were using with another call to the swapCursor()
                    adapter.swapCursor(null);
                }
            };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.item_contact);

        setupCursorAdapter();

        // Initialize the loader with a special ID and the defined callbacks from above
        getSupportLoaderManager().initLoader(CONTACT_LOADER_ID,
                new Bundle(), contactsLoader);

        // Find list and bind to adapter
        ListView lvContacts = (ListView) findViewById(R.id.lvContacts);

        if(lvContacts != null) {
            lvContacts.setAdapter(adapter);
        }
    }

    // Create simple cursor adapter to connect the cursor dataset we load with a ListView
    private void setupCursorAdapter() {
        // Column data from cursor to bind views from
        String[] uiBindFrom = { ContactsContract.Contacts.DISPLAY_NAME,
                ContactsContract.Contacts.PHOTO_URI };
        // View IDs which will have the respective column data inserted
        int[] uiBindTo = { R.id.tvName, R.id.ivImage };
        // Create the simple cursor adapter to use for our list
        // specifying the template to inflate (item_contact),
        adapter = new SimpleCursorAdapter(
                this, R.layout.item_contact,
                null, uiBindFrom, uiBindTo,
                0);
    }

    public static final int CONTACT_LOADER_ID = 78; // From docs: A unique identifier for this loader. Can be whatever you want.

}

item_contact.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ListView android:id="@+id/lvContacts"
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:layout_weight="1">
    </ListView>

    <!--android:background="#ff3399"-->

</LinearLayout>

simple_list_item_1.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView android:id="@+id/tvName"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:text="TextView"/>

    <TextView android:id="@+id/ivImage"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:text="TextView_callnumber"/>

</LinearLayout>

的AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.chris.contactswithcursorloader" >

    <uses-permission android:name="android.permission.READ_CONTACTS"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Answer 1

adapter = new SimpleCursorAdapter(
                this, R.layout.item_contact,
                null, uiBindFrom, uiBindTo,
                0);

布局应该是项目的布局，而不是活动的主要布局。你想在这里使用simple_list_item1。

Android活动和布局问题

1 个答案: