布局只显示复选框,不显示图像视图等。

huangapple go评论27阅读模式
英文:

Layout shows only CheckBox, does not show the ImageView etc

问题

我已经添加了布局和类别。我遇到的问题是,尽管我在布局中指定了它,但除了复选框之外,我看不到ImageView和TextViews。布局只显示复选框,不显示ImageViewTextView第二个TextView

项目页面CheckBox点击:

![项目页面CheckBox点击][1]

模拟器上的项目页面:

![模拟器上的项目页面][2]

AndroidStudio中的项目页面:

![AndroidStudio中的项目页面][3]

Drink Activity Layout是
XML:

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

    <ImageView
        android:id="@+id/photo"
        android:layout_width="190dp"
        android:layout_height="190dp"/>

    <TextView
        android:id="@+id/name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/description"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />


    <CheckBox android:id="@+id/favorite"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/favorite"
        android:onClick="onFavoriteClicked" />
</LinearLayout>

Drink Activity:

package com.hfad.starbuzz;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.view.View;
import android.widget.CheckBox;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.Objects;

public class DrinkActivity extends Activity {

    public static final String EXTRA_DRINKID = "drinkId";

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

        //从Intent中获取饮料
        int drinkId = (Integer) Objects.requireNonNull(getIntent().getExtras()).getInt(EXTRA_DRINKID);

        //创建一个游标
        SQLiteOpenHelper starbuzzDatabaseHelper = new StarbuzzDatabaseHelper(this);

        try {
            SQLiteDatabase db = starbuzzDatabaseHelper.getReadableDatabase();
            Cursor cursor = db.query("DRINK",
                    new String[]{"NAME","DESCRIPTION","IMAGE_RESOURCE_ID","FAVORITE"},
                    "_id = ?",
                    new String[]{Integer.toString(drinkId)},null,null,null);

            //移动游标到第一个条目
            if (cursor.moveToFirst()) {
                //从游标获取饮料详情
                String nameText = cursor.getString(0);
                String descriptionText = cursor.getString(1);
                int photoId = cursor.getInt(2);
                boolean isFavorite = (cursor.getInt(3) == 1);
                //填充饮料的名称
                TextView name = (TextView) findViewById(R.id.name);
                name.setText(nameText);
                //填充饮料的描述
                TextView description = (TextView) findViewById(R.id.description);
                description.setText(descriptionText);
                //填充饮料的图片
                ImageView photo = (ImageView) findViewById(R.id.photo);
                photo.setImageResource(photoId);
                photo.setContentDescription(nameText);
                //填充您最喜欢的饮料的标志
                CheckBox favorite = (CheckBox)findViewById(R.id.favorite);
                favorite.setChecked(isFavorite);
            }

            cursor.close();
            db.close();
        } catch (SQLiteException e) {
            Toast toast = Toast.makeText(this,
                    "不可用",
                    Toast.LENGTH_SHORT);
            toast.show();
        }
    }

    //单击复选框时刷新数据库
    public void onFavoriteClicked(View view){
        int drinkId = (Integer) Objects.requireNonNull(getIntent().getExtras()).getInt(EXTRA_DRINKID);
        //获取复选框的值
        CheckBox favorite = (CheckBox) findViewById(R.id.favorite);
        ContentValues drinkValues = new ContentValues();
        drinkValues.put("FAVORITE", favorite.isChecked());
        //检索数据库链接并更新FAVORITE列
        SQLiteOpenHelper starbuzzDatabaseHelper = new StarbuzzDatabaseHelper(this);
        try {
            SQLiteDatabase db = starbuzzDatabaseHelper.getWritableDatabase();
            db.update("DRINK",
                    drinkValues,
                    "_id = ?",
                    new String[] {Integer.toString(drinkId)});
            db.close();
        } catch(SQLiteException e) {
            Toast toast = Toast.makeText(this, "数据库不可用", Toast.LENGTH_SHORT);
            toast.show();
        }
    }
}

StarbuzzDatabaseHelper:

package com.hfad.starbuzz;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class StarbuzzDatabaseHelper extends SQLiteOpenHelper {
    private static final String DB_NAME = "starbuzz"; // 数据库名称
    // 增加版本号意味着SQLite助手将知道要更新数据库。
    private static final int DB_VERSION = 12; // 数据库版本和版本号。
    StarbuzzDatabaseHelper(Context context){
        super(context, DB_NAME, null, DB_VERSION);
    }

    @Override
    // 当数据库首次创建时调用onCreate()方法;
    // 我们用它来创建表格和插入数据
    public void onCreate(SQLiteDatabase db){
        updateMyDatabase(db, 0, DB_VERSION);
    }

    // 通过传递的参数从onUpgrade()调用updateMyDatabase()方法。
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        updateMyDatabase(db, oldVersion, newVersion);
    }

    // 由于需要插入多个饮料的数据,
    // 因此我们创建了一个单独的方法来插入数据。
    private static void insertDrink(SQLiteDatabase db, String name,
                                    String description, int resourceId) {
        ContentValues drinkValues = new ContentValues();
        drinkValues.put("NAME", name);
        drinkValues.put("DESCRIPTION", description);
        drinkValues.put("IMAGE_RESOURCE_ID", resourceId);
        db.insert("DRINK", null, drinkValues);
    }

    private void updateMyDatabase(SQLiteDatabase db, int oldVersion, int newVersion) {
        if (oldVersion < 1) {
            db.execSQL("CREATE TABLE DRINK (_id INTEGER PRIMARY KEY AUTOINCREMENT, "
                    + "NAME TEXT, "
                    + "DESCRIPTION TEXT, "
                    + "IMAGE_RESOURCE_ID INTEGER);");
            insertDrink(db, "Latte", "Espresso and steamed milk", R.drawable.latte);
            insertDrink(db, "

<details>
<summary>英文:</summary>

I have added layout and classes below. The problem I am having is that although I have specified it in the layout, I cannot see the ImageView and TextViews other than checkbox. Layout shows only **CheckBox**, does not show the **ImageView**, the **TextView** and **second TextView**!

Project page CheckBox clicked:

![project page CheckBox clicked][1]

Project page on emulator:

![project page on emulator][2]

Project page in AndroidStudio:

![project page in AndroidStudio][3]

Drink Activity Layout is
**XML:**

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
    &lt;LinearLayout xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
    xmlns:tools=&quot;http://schemas.android.com/tools&quot;
    android:layout_width=&quot;match_parent&quot;
    android:layout_height=&quot;match_parent&quot;
    android:orientation=&quot;vertical&quot;
    tools:context=&quot;com.hfad.starbuzz.DrinkActivity&quot; &gt;
    
    &lt;ImageView
    android:id=&quot;@+id/photo&quot;
    android:layout_width=&quot;190dp&quot;
    android:layout_height=&quot;190dp&quot;/&gt;
    
    &lt;TextView
    android:id=&quot;@+id/name&quot;
    android:layout_width=&quot;match_parent&quot;
    android:layout_height=&quot;wrap_content&quot; /&gt;
    
    &lt;TextView
    android:id=&quot;@+id/description&quot;
    android:layout_width=&quot;match_parent&quot;
    android:layout_height=&quot;wrap_content&quot; /&gt;
    
    
    &lt;CheckBox android:id=&quot;@+id/favorite&quot;
    android:layout_width=&quot;wrap_content&quot;
    android:layout_height=&quot;wrap_content&quot;
    android:text=&quot;@string/favorite&quot;
    android:onClick=&quot;onFavoriteClicked&quot; /&gt;
    &lt;/LinearLayout&gt;


**Drink Activity:**   

    package com.hfad.starbuzz;
    import android.app.Activity;
    import android.content.ContentValues;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteException;
    import android.database.sqlite.SQLiteOpenHelper;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.CheckBox;
    import android.widget.ImageView;
    import android.widget.TextView;
    import android.widget.Toast;
    import java.util.Objects;
    
    public class DrinkActivity extends Activity {
    
        public static final String EXTRA_DRINKID = &quot;drinkId&quot;;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_drink);
    
            //Getting a drink from an intent
            int drinkId = (Integer) Objects.requireNonNull(getIntent().getExtras()).getInt(EXTRA_DRINKID);
    
            //Creating a cursor
            SQLiteOpenHelper starbuzzDatabaseHelper = new StarbuzzDatabaseHelper(this);
    
            try {
                SQLiteDatabase db = starbuzzDatabaseHelper.getReadableDatabase();
                Cursor cursor = db.query(&quot;DRINK&quot;,
                        new String[]{&quot;NAME&quot;,&quot;DESCRIPTION&quot;,&quot;IMAGE_RESOURCE_ID&quot;,&quot;FAVORITE&quot;},
                        &quot;_id = ?&quot;,
                        new String[]{Integer.toString(drinkId)},null,null,null);
    
            
    
            //Move to the first entry in the cursor
            if (cursor.moveToFirst()) {
            //Get the drink details from the cursor
            String nameText = cursor.getString(0);
            String descriptionText = cursor.getString(1);
            int photoId = cursor.getInt(2);
            boolean isFavorite = (cursor.getInt(3) == 1);
            //Filling in the name of the drink
            TextView name = (TextView) findViewById(R.id.name);
            name.setText(nameText);
            //Filling in the description of the drink
            TextView description = (TextView) findViewById(R.id.description);
            description.setText(descriptionText);
            //Filling the drink image
            ImageView photo = (ImageView) findViewById(R.id.photo);
            photo.setImageResource(photoId);
            photo.setContentDescription(nameText);
            //Filling the Flag for Your Favorite Drink
            CheckBox favorite = (CheckBox)findViewById(R.id.favorite);
            favorite.setChecked(isFavorite);
            }
                
    
            cursor.close();
                db.close();
            } catch (SQLiteException e) {
                Toast toast = Toast.makeText(this,
                        &quot; unavailable&quot;,
                        Toast.LENGTH_SHORT);
                toast.show();
            }
        }
    
        //Database refresh on click of a checkbox
        public void onFavoriteClicked(View view){
            int drinkId = (Integer) Objects.requireNonNull(getIntent().getExtras()).getInt(EXTRA_DRINKID);
            //Getting the value of a checkbox
            CheckBox favorite = (CheckBox) findViewById(R.id.favorite);
            ContentValues drinkValues = new ContentValues();
            drinkValues.put(&quot;FAVORITE&quot;, favorite.isChecked());
            //Retrieving a database link and updating the FAVORITE column
            SQLiteOpenHelper starbuzzDatabaseHelper = new StarbuzzDatabaseHelper(this);
            try {
                SQLiteDatabase db = starbuzzDatabaseHelper.getWritableDatabase();
                db.update(&quot;DRINK&quot;,
                        drinkValues,
                        &quot;_id = ?&quot;,
                        new String[] {Integer.toString(drinkId)});
                db.close();
            } catch(SQLiteException e) {
                Toast toast = Toast.makeText(this, &quot;Database unavailable&quot;, Toast.LENGTH_SHORT);
                toast.show();
            }
        }
    }

**StarbuzzDatabaseHelper:**

    package com.hfad.starbuzz;
    import android.content.ContentValues;
    import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;
    
    public class StarbuzzDatabaseHelper extends SQLiteOpenHelper {
        private static final String DB_NAME = &quot;starbuzz&quot;; // Database name
        //Increasing the version number means that the SQLite Assistant will know to update the database.
        private static final int DB_VERSION = 12; // Database version and version number.
        StarbuzzDatabaseHelper(Context context){
            super(context, DB_NAME, null, DB_VERSION);
        }
    
        @Override
        //The onCreate () method is called when the database is first created;
        //We use it to create a table and insert data
        public void onCreate(SQLiteDatabase db){
            updateMyDatabase(db, 0, DB_VERSION);
        }
    
        //The updateMyDatabase () method is called from onUpgrade () with parameters passed.
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            updateMyDatabase(db, oldVersion, newVersion);
        }
    
        //It is necessary to insert the data of several drinks,
        //so we created a separate method for inserting.
        private static void insertDrink(SQLiteDatabase db, String name,
                                        String description, int resourceId) {
            ContentValues drinkValues = new ContentValues();
            drinkValues.put(&quot;NAME&quot;, name);
            drinkValues.put(&quot;DESCRIPTION&quot;, description);
            drinkValues.put(&quot;IMAGE_RESOURCE_ID&quot;, resourceId);
            db.insert(&quot;DRINK&quot;, null, drinkValues);
        }
    
        private void updateMyDatabase(SQLiteDatabase db, int oldVersion, int newVersion) {
            if (oldVersion &lt; 1) {
                db.execSQL(&quot;CREATE TABLE DRINK (_id INTEGER PRIMARY KEY AUTOINCREMENT, &quot;
                        + &quot;NAME TEXT, &quot;
                        + &quot;DESCRIPTION TEXT, &quot;
                        + &quot;IMAGE_RESOURCE_ID INTEGER);&quot;);
                insertDrink(db, &quot;Latte&quot;, &quot;Espresso and steamed milk&quot;, R.drawable.latte);
                insertDrink(db, &quot;Cappuccino&quot;, &quot;Espresso, hot milk and steamed-milk foam&quot;,
                        R.drawable.cappuccino);
                insertDrink(db, &quot;Filter&quot;, &quot;Our best drip coffee&quot;, R.drawable.filter);
            }
            //This code is executed if the user already has version 1 of the database installed
            if (oldVersion &gt;= 2) {
            }
            //Code for adding a new column
        }
    }

  [1]: https://i.stack.imgur.com/YLieU.png
  [2]: https://i.stack.imgur.com/4GWfV.png
  [3]: https://i.stack.imgur.com/p00ej.png



</details>


# 答案1
**得分**: 1

你的查询是否返回任何数据?您可能需要检查cursor.getCount()的输出。

另外,如果您进入设备的开发者选项,您可以看到一个名为"显示布局边界"的选项它会显示您的视图元素在屏幕上的位置

<details>
<summary>英文:</summary>

Is your query returning any data? You might want to check the output of cursor.getCount().

Also if you go into Developer Options of your device you can see an option called &quot;Show Layout Bounds&quot;. It will show you where your view elements are on the screen.

</details>



# 答案2
**得分**: 0

I finally found a solution, in public class StarbuzzDatabaseHelper

```java
private static final int DB_VERSION = 12;

change to:

private static final int DB_VERSION = 2;

if (oldVersion >= 2) {

change to:

if (oldVersion < 2) {
db.execSQL("ALTER TABLE DRINK ADD COLUMN FAVORITE NUMERIC;");
}


<details>
<summary>英文:</summary>
I finally found a solution, in public class StarbuzzDatabaseHelper
&#39;&#39;&#39;&#39;
private static final int DB_VERSION = 12;
&#39;&#39;&#39;&#39;
change to: private static final int DB_VERSION = 2;
&#39;&#39;&#39;&#39;
if (oldVersion &gt;= 2) {
}
&#39;&#39;&#39;&#39;
change to: if (oldVersion &lt; 2) {
db.execSQL(&quot;ALTER TABLE DRINK ADD COLUMN FAVORITE NUMERIC;&quot;);
}
&#39;&#39;&#39;&#39;
</details>

huangapple
  • 本文由 发表于 2020年7月30日 20:42:13
  • 转载请务必保留本文链接:https://go.coder-hub.com/63173410.html
匿名

发表评论

匿名网友

:?: :razz: :sad: :evil: :!: :smile: :oops: :grin: :eek: :shock: :???: :cool: :lol: :mad: :twisted: :roll: :wink: :idea: :arrow: :neutral: :cry: :mrgreen:

确定