Android 安卓DataBinding（五）·单向绑定 ObservableCollection（集合使用）

小鱼儿 2023-06-01 12:40 29阅读 0赞

### 文章目录 ###

*   *  前景回顾
     *  单向绑定
     *   *  ObservableMap
         *   *  ObservableMap 运行效果
         *  ObservableList
         *   *  ObservableList 运行效果
         *  更新UI
         *  更新UI运行效果

--------------------

## 前景回顾 ##

[Android 安卓DataBinding（一）·基础][Android _DataBinding]  
[Android 安卓DataBinding（二）·入门][Android _DataBinding 1]  
[Android 安卓DataBinding（三）·单向绑定 BaseObservable][Android _DataBinding_ BaseObservable]  
[Android 安卓DataBinding（四）·单向绑定 ObservableField][Android _DataBinding_ ObservableField]

上一期讲到 **ObservableField** 单向绑定，和 **BaseObservable** 相比之下，**ObservableField** 简单了许多，只需要用它的方法即可，提供了自动刷新UI的方法。  
如果用到 Map 或者是 List，同样 **DataBinding** 还提供了 **ObservableMap** 和 **ObservableList**，下面来基本使用一下吧！

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## 单向绑定 ##

使用单向绑定刷新UI有三种

1.  使用 [BaseObservable][Android _DataBinding_ BaseObservable]
2.  使用 [ObservableField][Android _DataBinding_ ObservableField]
3.  使用 ObservableCollection

--------------------

### ObservableMap ###

写出布局文件，布局文件添加 android.databinding.ObservableMap 包，然后再使用variable标签引用 ：  
还是一样，如果是int类型，要转成String类型，否则会报错！

<?xml version="1.0" encoding="utf-8"?>
    <layout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools">
    
        <data>
    
            <import type="android.databinding.ObservableMap" />
    
            
            <variable name="people" type="ObservableMap<String,Object>" />
    
        </data>
    
        <android.support.constraint.ConstraintLayout android:layout_width="match_parent" android:layout_height="match_parent" android:background="#FFFFFF" tools:context=".MainActivity">
    
            <TextView android:id="@+id/name1" android:layout_width="match_parent" android:layout_height="50dp" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="20dp" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" android:background="#03A9F4" android:gravity="center" android:text='@{String.valueOf(people["NorthernBrain1"])}' android:textColor="#FFFFFF" android:textStyle="bold" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" tools:ignore="MissingConstraints" />
    
            <TextView android:id="@+id/name2" android:layout_width="match_parent" android:layout_height="50dp" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" android:background="#03A9F4" android:gravity="center" android:text='@{people["NorthernBrain2"]}' android:textColor="#FFFFFF" android:textStyle="bold" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/name1" tools:ignore="MissingConstraints" />
    
            <TextView android:id="@+id/name3" android:layout_width="match_parent" android:layout_height="50dp" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" android:background="#03A9F4" android:gravity="center" android:text='@{people["NorthernBrain3"]}' android:textColor="#FFFFFF" android:textStyle="bold" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/name2" tools:ignore="MissingConstraints" />
    
            <TextView android:id="@+id/name4" android:layout_width="match_parent" android:layout_height="50dp" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" android:background="#03A9F4" android:gravity="center" android:text='@{String.valueOf(people["NorthernBrain4"])}' android:textColor="#FFFFFF" android:textStyle="bold" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/name3" tools:ignore="MissingConstraints" />
    
    
        </android.support.constraint.ConstraintLayout>
    </layout>

--------------------

写一段demo，用到 ObservableMap<String,Object> ，如下放进去四条信息：

package com.lkdot.data;
    
    import android.annotation.SuppressLint;
    import android.databinding.DataBindingUtil;
    import android.databinding.ObservableArrayMap;
    import android.databinding.ObservableMap;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.View;
    
    import com.lkdot.data.databinding.ActivityMainBinding;
    
    public class MainActivity extends AppCompatActivity { 
    
        private ActivityMainBinding activityMainBinding;
        private ObservableMap<String, Object> people;
    
        @SuppressLint({ "SetTextI18n", "InlinedApi"})
        @Override
        protected void onCreate(Bundle savedInstanceState) { 
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            activityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main);
    
            //这句不用管，是关于安卓状态栏的
            getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);
    
            people = new ObservableArrayMap<>();
            people.put("NorthernBrain1", 25);
            people.put("NorthernBrain2", "NorthernBrain2 = 26");
            people.put("NorthernBrain3", "NorthernBrain3 = 27");
            people.put("NorthernBrain4", 28);
    
            activityMainBinding.setPeople(people);
    
        }
    }

--------------------

#### ObservableMap 运行效果 ####

![在这里插入图片描述][20191003144934237.jpg]

--------------------

### ObservableList ###

布局文件稍微改动以下，导入 **ObservableList** ，老规矩，如果你用的是int类型的值，就转成String，这里是String类型的值：

<?xml version="1.0" encoding="utf-8"?>
    <layout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools">
    
        <data>
    
            <import type="android.databinding.ObservableList" />
    
            
            <variable name="people" type="ObservableList<String>" />
    
        </data>
    
        <android.support.constraint.ConstraintLayout android:layout_width="match_parent" android:layout_height="match_parent" android:background="#FFFFFF" tools:context=".MainActivity">
    
            <TextView android:id="@+id/name1" android:layout_width="match_parent" android:layout_height="50dp" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="20dp" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" android:background="#03A9F4" android:gravity="center" android:text='@{people[0]}' android:textColor="#FFFFFF" android:textStyle="bold" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" tools:ignore="MissingConstraints" />
    
            <TextView android:id="@+id/name2" android:layout_width="match_parent" android:layout_height="50dp" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" android:background="#03A9F4" android:gravity="center" android:text='@{people[1]}' android:textColor="#FFFFFF" android:textStyle="bold" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/name1" tools:ignore="MissingConstraints" />
    
            <TextView android:id="@+id/name3" android:layout_width="match_parent" android:layout_height="50dp" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" android:background="#03A9F4" android:gravity="center" android:text='@{people[2]}' android:textColor="#FFFFFF" android:textStyle="bold" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/name2" tools:ignore="MissingConstraints" />
    
            <TextView android:id="@+id/name4" android:layout_width="match_parent" android:layout_height="50dp" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" android:background="#03A9F4" android:gravity="center" android:text='@{people[3]}' android:textColor="#FFFFFF" android:textStyle="bold" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/name3" tools:ignore="MissingConstraints" />
    
    
        </android.support.constraint.ConstraintLayout>
    </layout>

--------------------

修改 MainActivity.java，稍微变动一下即可：

package com.lkdot.data;
    
    import android.annotation.SuppressLint;
    import android.databinding.DataBindingUtil;
    import android.databinding.ObservableArrayList;
    import android.databinding.ObservableList;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.View;
    
    import com.lkdot.data.databinding.ActivityMainBinding;
    
    public class MainActivity extends AppCompatActivity { 
    
        private ActivityMainBinding activityMainBinding;
        private ObservableList<String> people;
    
        @SuppressLint({ "SetTextI18n", "InlinedApi"})
        @Override
        protected void onCreate(Bundle savedInstanceState) { 
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            activityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main);
    
            //这句不用管，是关于安卓状态栏的
            getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);
    
            people = new ObservableArrayList<>();
            people.add("NorthernBrain1");
            people.add("NorthernBrain2");
            people.add("NorthernBrain3");
            people.add("NorthernBrain4");
    
            activityMainBinding.setPeople(people);
        }
    }

--------------------

#### ObservableList 运行效果 ####

![在这里插入图片描述][20191003145950387.jpg]

--------------------

### 更新UI ###

下面呢，我写出一个更新UI的操作，这里以 **ObservableList** 为例，Map也一样。  
加上点击事件：

--------------------

布局文件增加按钮和事件：

### 更新UI运行效果 ###

![在这里插入图片描述][2019100315420946.gif]  
**[下一篇文章 Android 安卓DataBinding（六）·双向绑定][Android _DataBinding 2]**

[Android _DataBinding]: https://blog.csdn.net/qq_40881680/article/details/101714634
[Android _DataBinding 1]: https://blog.csdn.net/qq_40881680/article/details/101781705
[Android _DataBinding_ BaseObservable]: https://blog.csdn.net/qq_40881680/article/details/101800669
[Android _DataBinding_ ObservableField]: https://blog.csdn.net/qq_40881680/article/details/101847386
[20191003144934237.jpg]: /images/20230601/afc0d1e6570147f9a9093682dc349250.png
[20191003145950387.jpg]: /images/20230601/5f10a1e61d3d46729eb0a36c143b8403.png
[2019100315420946.gif]: /images/20230601/cfcec42d86b94de0bd70cc3491ac83da.png
[Android _DataBinding 2]: https://blog.csdn.net/qq_40881680/article/details/102010622