How to use addView to add view to layout?

问题

I have read probably all posts and documentation but I still can't solve this issue.

I want to use addView() method to add view to the existing (running) layout but for some reason I cant. I know that this should be easy and basic but still I cant do it. So, please help me.

Here is a code:

LinearLayout layout = (LinearLayout)findViewById(R.id.mainLayout);
TextView text       = new TextView(this);
text.setText("test");
layout.addView(text);

That's a code, and the result is that I have displayed only views which are defined in XML file. There is no this new view I have added. When I debug I see this added view as a child of the parent to which I have added it but it isn't displayed.

here is main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads"
                android:id="@+id/mainLayout"
              android:layout_width="fill_parent" 
              android:layout_height="fill_parent"
              android:orientation="vertical"
              android:background="@drawable/main1" >
    <TextView android:id="@+id/app_title"
              android:layout_width="fill_parent"
              android:layout_height="wrap_content"
              android:textColor="#FFF"
              android:text="@string/app_title"
              android:textSize="25dp" 
              android:gravity="center_horizontal"/>
    <TextView android:layout_width="fill_parent" 
              android:layout_height="wrap_content"
              android:layout_marginTop="5dp"
              android:text="@string/main_screen_counter_title"
              android:textSize="15dp" 
              android:textColor="#FFF"
              android:gravity="center_horizontal"/>
   <TextView android:id="@+id/frontScreenCounter"
              android:layout_width="fill_parent" 
              android:layout_height="wrap_content"
              android:textColor="#FFF"
              android:text="@string/reading"
              android:textSize="33dp"
              android:gravity="center_horizontal" />   
    <GridView android:id="@+id/gridview"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:columnWidth="90dp"
    android:numColumns="3"
    android:verticalSpacing="10dp"
    android:horizontalSpacing="10dp"
    android:stretchMode="columnWidth"
    android:gravity="center"
    android:textColor="#888"
/>
</LinearLayout>

Please help. This will driving me nuts!

回答1:

You forgot to specify the LayoutParameters for the newly added view.

LinearLayout layout = (LinearLayout)findViewById(R.id.mainLayout);
    TextView text=new TextView(this);
    text.setLayoutParams(new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
    text.setText("test");
    layout.addView(text);

EDIT

The GridView with an id of @+id/gridview is defined with a layout height of fill_parent, leaving you with no space to add a new view. Changing its height to wrap_content may solve your problem.

Adding my comment to this post to help others easily verify the solution.

回答2:

I had the same problem and wasted several time finding the reason.

My fault was that I was adding a CustomView that had match_parent set as height.

I hope to save some precious time to anybody who did this silly annoying mistake :)

TextView tv = new TextView(this);
lytMarks.addView(tv);


CustomView cv = new CustomView(this, someObject);
lytMarks.addView(cv); // <-- This one had height = match_parent!!


EditText et = new EditText(this);
lytMarks.addView(et);

回答3:

Your linearLayout content is over the parent's View. so you need to use ScrollView. like this:

<?xml version="1.0" encoding="utf-8"?>

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads"
android:layout_width="fill_parent"
android:layout_height="fill_parent">

<LinearLayout
    android:id="@+id/mainLayout"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/main1"
    android:orientation="vertical">

    <TextView
        android:id="@+id/app_title"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:text="@string/app_title"
        android:textColor="#FFF"
        android:textSize="25dp" />

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        android:gravity="center_horizontal"
        android:text="@string/main_screen_counter_title"
        android:textColor="#FFF"
        android:textSize="15dp" />

    <TextView
        android:id="@+id/frontScreenCounter"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:text="@string/reading"
        android:textColor="#FFF"
        android:textSize="33dp" />

    <GridView
        android:id="@+id/gridview"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:columnWidth="90dp"
        android:gravity="center"
        android:horizontalSpacing="10dp"
        android:numColumns="3"
        android:stretchMode="columnWidth"
        android:textColor="#888"
        android:verticalSpacing="10dp" />
</LinearLayout>
</ScrollView>