Question

如果我单击Activity-3后退按钮，则它将转到Activity-1，而不是Activity-2。我不确定清单文件中有什么问题。如果单击“后退”按钮，则会出现错误。下面是“活动”页面2中的错误代码。如果单击该项目，则Recycler视图工作正常。现在的问题只是向后。
找到了问题。从Activity3到Activity2的变量为空，因此这就是它进入Activity1的原因。

Activity:3
        TestMenuDetail:
        val navBarTitle2=intent.getStringExtra(TestMenuViewHolder.TEST_TITLE_NAME)
        val TestVar=Intent(this@TestMenuDetail,TestMenuList::class.java)
        intent.putExtra("TestVar",navBarTitle2)

Activity:2      
TestMenuList:
        val navBarTitle3=intent.getStringExtra("TestVar")
        println("Helllo Test: $navBarTitle3")







Process: TestProject, PID: 28725
    com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was NUMBER at line 1 column 2 path $
        at com.google.gson.Gson.fromJson(Gson.java:939)
        at com.google.gson.Gson.fromJson(Gson.java:892)
        at com.google.gson.Gson.fromJson(Gson.java:841)
        at com.google.gson.Gson.fromJson(Gson.java:813)
        at TestProject.TestMenuList$fetchJSON$1.onResponse(TestMenuList.kt:50)
        at okhttp3.RealCall$AsyncCall.execute(RealCall.java:153)
        at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at java.lang.Thread.run(Thread.java:764)
     Caused by: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was NUMBER at line 1 column 2 path $
        at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:350)
        at com.google.gson.internal.bind.ArrayTypeAdapter.read(ArrayTypeAdapter.java:70)
        at com.google.gson.Gson.fromJson(Gson.java:927)
        at com.google.gson.Gson.fromJson(Gson.java:892) 
        at com.google.gson.Gson.fromJson(Gson.java:841) 
        at com.google.gson.Gson.fromJson(Gson.java:813) 
        at TestProject.TestMenuList$fetchJSON$1.onResponse(TestMenuList.kt:50) 
        at okhttp3.RealCall$AsyncCall.execute(RealCall.java:153) 
        at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32) 
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641) 
        at java.lang.Thread.run(Thread.java:764) 


 Android Manifest.XML
Activity:1       
       <activity
            android:name="TestProject.ItemDetailActivity3"
            android:label="Item Price"
            android:screenOrientation="portrait">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="TestProject.WelcomeActivity" />
        </activity>
Activity:2
        <activity
            android:name="TestProject.TestMenuList"
            android:label="Test Menu"
            android:screenOrientation="portrait">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="TestProject.ItemDetailActivity3" />
        </activity>
Activity:3
        <activity android:name="TestProject.TestMenuDetail"
            android:label="Test List Detail"
            android:screenOrientation="portrait" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="TestProject.TestMenuList" />
        </activity>

Answer 1

使用android:parentActivityName：

<activity android:name="TestProject.TestMenuDetail"
            android:label="Test List Detail"
            android:screenOrientation="portrait" 
            android:parentActivityName="TestProject.TestMenuList"> // your activity which you want to get back to

            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="TestProject.TestMenuList" />
      </activity>

Answer 2

您不需要上级活动即可导航/返回。但是，如果需要，则需要指定android:parentActivityName属性，否则它不适用于4.0以上的Android版本。来自Google Docs：

<application ... >
    ...
    <!-- The main/home activity (it has no parent activity) -->
    <activity
        android:name="com.example.myfirstapp.MainActivity" ...>
        ...
    </activity>
    <!-- A child of the main activity -->
    <activity
        android:name="com.example.myfirstapp.DisplayMessageActivity"
        android:label="@string/title_activity_display_message"
        android:parentActivityName="com.example.myfirstapp.MainActivity" >
        <!-- Parent activity meta-data to support 4.0 and lower -->
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.myfirstapp.MainActivity" />
    </activity>
</application>

其他向上导航的方法是使用后退按钮实现。考虑到您会将活动堆叠在另一个活动的顶部，

在OnCreate方法内部添加以下内容：

if (getSupportActionBar() != null) 
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

然后覆盖OnOptionsItemSelected来执行操作：

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    // Respond to the action bar's Up/Home button
    case android.R.id.home:
        finish();
        return true;
    }
    return super.onOptionsItemSelected(item);
}

AndroidManifest.xml备份按钮不起作用

2 个答案: