Android DataBinding， View 标签在 View :null 上不正确

Question

我正在尝试创建一个带有数据绑定(bind)的自定义 View 。这是自定义 View 的代码:

package com.xxx.myapplication;

import android.content.Context;
import android.databinding.DataBindingUtil;
import android.util.AttributeSet;
import android.widget.FrameLayout;

import com.xxx.myapplication.databinding.DataviewBinding;

/**
 * Created by atp on 12/25/2016.
*/
public class DataView extends FrameLayout {
    DataviewBinding binding;

    public DataView(Context context) {
        super(context);
    }

    public DataView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public DataView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public DataView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
    super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        binding =  DataviewBinding.bind(this);
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        Customer customer = new Customer();
        customer.firstName = "Custom view ";
        binding.setDataSource(customer);
    }
}

我创建了一个布局文件 dataview.xml 并在其中使用了上面的自定义 View :

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:tools="http://schemas.android.com/tools">
    <data>
        <variable
            name="dataSource"
            type="com.xxx.myapplication.Customer" />
    </data>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <com.xxx.myapplication.DataView
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="@{dataSource.firstName}" />
        </com.xxx.myapplication.DataView>
    </LinearLayout>
</layout>

然后我将 dataview.xml 包含在我的 Activity 布局中:

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:bind="http://schemas.android.com/apk/res-auto">

    <RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin">

        <include layout="@layout/dataview"/>
    </RelativeLayout>
</layout>

但是当我运行程序时，出现以下异常:

java.lang.RuntimeException: Unable to start activity ComponentInfo{---}:android.view.InflateException: Binary XML file line #13: view tag isn't correct on view:null
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2464)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2524)
at android.app.ActivityThread.access$900(ActivityThread.java:154)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1391)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:234)
at android.app.ActivityThread.main(ActivityThread.java:5526)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: android.view.InflateException: Binary XML file line #13: view tag isn't correct on view:null
at android.view.LayoutInflater.inflate(LayoutInflater.java:539)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:284)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140)
at com.xxx.myapplication.MainActivity.onCreate(MainActivity.java:16)
at android.app.Activity.performCreate(Activity.java:6285)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2524) 
at android.app.ActivityThread.access$900(ActivityThread.java:154) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1391) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:234) 
at android.app.ActivityThread.main(ActivityThread.java:5526) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
Caused by: java.lang.RuntimeException: view tag isn't correct on view:null
at com.xxxx.myapplication.databinding.DataviewBinding.bind(DataviewBinding.java:128)
at com.xxx.myapplication.databinding.DataviewBinding.bind(DataviewBinding.java:124)
at com.xxx.myapplication.DataView.onFinishInflate(DataView.java:35)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:844)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:838)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.parseInclude(LayoutInflater.java:971)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:831)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:374) 
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:284) 
at  android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140) 
at com.xxx.myapplication.MainActivity.onCreate(MainActivity.java:16) 
at android.app.Activity.performCreate(Activity.java:6285) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2524) 
at android.app.ActivityThread.access$900(ActivityThread.java:154) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1391)     
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:234) 
at android.app.ActivityThread.main(ActivityThread.java:5526) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

Answer 1

通常你会收到这个错误，因为你试图将你的 DataBinding 绑定(bind)到一个已经有另一个 DataBinding 连接到它的 View 。

为了确保没有任何内容已绑定(bind)到您的 View ，请尝试 DataBindingUtil.getBinding(view)。它将返回 View 的当前 DataBinding，因此您可以重用它而不是尝试创建新的 DataBinding。