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In XML Button size changes with its Font size

I know this sounds simple but I wanted to change a button's font size to fill the Button .Even though the text doesn't take all the space inside the button when I decrease text height for example the Button's height decreases as well.Is there any way I can change The text-size so it fills that space inside the Button or do I have to just use an Image Button .
Here is the case :-
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:background="#android:color/black"
android:id="#+id/led"
>
<Button
android:id="#+id/grow"
android:layout_width="match_parent"
android:layout_height="39dp"
android:layout_marginRight="1dp"
android:layout_weight="1"
android:textSize="15dp"
android:background="#color/Lightbrown"
android:text="A▲"
android:textAllCaps="false"
/>
<Button
android:layout_width="match_parent"
android:layout_height="39dp"
android:text="A▼"
android:textAllCaps="false"
android:id="#+id/shrink"
android:background="#color/Lightbrown"
android:layout_marginRight="1dp"
android:layout_weight="1"
android:padding="0dp"
android:textSize="10dp"
/>
See I used my Linearlayout as a background for my Buttons the second button's size changes with its font size I just want its size to remain the same as the first Button but with a smaller textsize.

Update
Your second button is not actually smaller, it is just aligned in a way you wouldn't necessarily expect.
Horizontal LinearLayouts with TextView (or subclass, which Button is) children will "baseline align" the children. That means they will make sure that the bottom edge of all the text in the row is at the same height. Since your second button uses smaller text, the text bottom would be higher up inside the button, so the LinearLayout forces the whole button down to accomodate.
Add this attribute to your LinearLayout:
android:baselineAligned="false"
Original
First, I assume you're using android:layout_height="wrap_content". If you don't want your button's height to scale with font size, you'll have to change this to some fixed value (or match_parent if you want it to be the same size as its parent).
As for why the text "doesn't take up all the space", that's because Buttons have padding built into them automatically. You can remove this padding by defining android:padding="0dp"
However, you'll soon notice that the button looks really bad if you give it no padding and too-large text. How to solve that is really up to the requirements of your design.
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:layout_width="wrap_content"
android:layout_height="32dp"
android:layout_gravity="center_horizontal"
android:padding="0dp"
android:textSize="36sp"
android:text="Hello world"/>
</FrameLayout>

Use a fixed size instead of wrap_content for your button.
f that doesn't work for your design, consider overlaying a TextView on top of your Button (with ConstraintLayout or FrameLayout or RelativeLayout). After that, you can set the TextView's focusable, focusableInTouchMode, and clickable properties to false so that it doesn't intercept your Button's clicks.

LinearLayout clipping children with TextView width set to wrap_content

I have a LinearLayout which contains a TextView and an ImageView. The TextView width is set to wrap_content, but the issue is when the width reaches the parent width. The text content will correctly wrap to 2 or more lines, but the TextView and ImageView will be clipped on the left and right sides. The most similar question I could find was this one, which is from 2013 and has no solution.
Specifically, I'm experiencing the issue on this view, but I've created the following simpler view to exemplify the problem:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/card_top_holder"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:orientation="horizontal">
<TextView
android:id="#+id/card_top_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="One Two Three Four Five"
android:textSize="40sp"/>
<ImageView
android:layout_width="24dp"
android:layout_height="24dp"
android:src="#drawable/ic_volume_up_black_48dp"/>
</LinearLayout>
Here is the problem:
Here is the layout normally:
When the layout overlaps another view, setting android:clipChildren="false" on the LinearLayout doesn't even prevent the clipping.
And here is one final image to prove it's happening on a real device and not just the layout viewer:
I'm basically out of ideas. Any thoughts? Is this an issue with the Android layout system? Thanks for the help and consideration!

You can achieve the desired result using android:layout_weight
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/card_top_holder"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:orientation="horizontal">
<TextView
android:id="#+id/card_top_text"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="One Two Three Four Five"
android:textSize="40sp"/>
<ImageView
android:layout_width="24dp"
android:layout_height="24dp"
android:src="#drawable/ic_volume_up_black_48dp"/>
</LinearLayout>
Edit: A little quote from the docs about how layout_weight works
LinearLayout also supports assigning a weight to individual children with the android:layout_weight attribute. This attribute assigns an "importance" value to a view in terms of how much space it should occupy on the screen. A larger weight value allows it to expand to fill any remaining space in the parent view. Child views can specify a weight value, and then any remaining space in the view group is assigned to children in the proportion of their declared weight. Default weight is zero.
For example, if there are three text fields and two of them declare a weight of 1, while the other is given no weight, the third text field without weight will not grow and will only occupy the area required by its content. The other two will expand equally to fill the space remaining after all three fields are measured. If the third field is then given a weight of 2 (instead of 0), then it is now declared more important than both the others, so it gets half the total remaining space, while the first two share the rest equally.

Android RelativeLayout: Rightmost child takes all the extra space no matter what I do

I have a RelativeLayout with three child views laid out horizontally. I want the leftmost one to take up any extra space and the other two to take up only the space needed to wrap their content. The documentation says this can be done, but I can't make it work. Here's what I have:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="6dp"
android:textStyle="bold"
android:layoutDirection="rtl">
<TextView
android:id="#+id/nodeLabel"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="#dimen/text_size"
android:gravity="fill_horizontal"
android:layout_alignParentLeft="true" />
<Button
android:id="#+id/launch"
android:text="#string/launch_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="#id/nodeLabel"
android:gravity="left" />
<Button
android:id="#+id/kill"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="#id/launch"
android:layout_alignParentRight="true"
android:text="#string/kill_label"
android:gravity="left" />
</RelativeLayout>
The result is the TextView takes up all the space, and the two Buttons are not rendered at all. If I change android:layout_width on the TextView from match_parent to wrap_content, then all three Views show up, but the third one, the Button, takes the extra space, which is not what I want. I also tried setting layout_width on the Buttons to 0dp, and experimented with other settings values, all to no avail.
How can I make the two Buttons no bigger than needed to wrap their content, and have the TextView take up the extra space?

add the propery android:layout_weight="x".
It works like this:
if there are 4 views in a row and every one has a weight of 1. Then every view occupies 1/4 of the space. If one has a weight of 2 then it occupies 2/5 and so on. If one has a weight of 0 or no weight, then it just occupies as much space as its content does. The system adds all the weights together and then sets every view the proportional width.
In your case you have to weigh them something like 1, 0, 0.

match_parent not performing as expected

I imagine this should be a fairly easy one to answer, if you understand XML Layouts better than I do that is. I don't seem to get what I was thinking I should when using the match_parent layout_height.
I have a LinearLayout root element with android:orientation="vertical". Inside this LinearLayout I want three elements:
- TextView
- ListView
- TextView
For both the TextViews I set android:layout_height="wrap_content" so that they will be only as tall as is necessary to display their contents. The thing is, I want the one TextView to sit at the top of the form, the other one to sit at the bottom of the form while the ListView fills up whatever space is available on the form. So here is what my xml layout looks like:
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="30sp"
android:text="Top TextView" />
<ListView
android:id="#+id/listView_Species"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="30sp"
android:text="Bottom TextView" />
But it doesn't work. Here's what I get. I've selected the ListView so that it will be highlighted. Notice how it extends all the way to the bottom of the form, pushing the bottom TextView off the form.
When I change the layout_height property of the ListView to some fixed value, like 180dp, this is what the form looks like. I'm just posting this to prove that the bottom TextView is there but I still don't know how to get it to be fixed to the bottom of the screen while the ListView takes up whatever space remains, but in between the two TextViews.
Thanks in advance.

While the other answers try to fix your problem (which they don't actually--they suggest you do something that looks similar but may or may not look good on different devices), no one has filled in the gaps in your knowledge of LinearLayouts and match_parent. And these gaps are very common--Google's documentation is still far below stellar.
First, how do Views work within a LinearLayout? Let's go through the process of drawing a LinearLayout, using orientation="vertical" for simplicity.
Examine the height of the first child of the LinearLayout (LL for short). If the height is match_parent or fill_parent (old name for the same thing) then the height of the View is stretched to fill the entire viewing area. If the height is wrap_content, then measure the vertical space the View takes and use that space for the View. If the height is a non-zero number, use exactly that many pixels for the View's height (may clip if too small). If the height is 0 see below.
Put the next view below the view in 1. Check its height and act accordingly.
Continue for all the Views. If a View is pushed off the bottom, go ahead and stop calculating because no one will see it or any succeeding Views (assuming no ScrollView).
If the height of a View is 0, check it's gravity. This requires a second pass, storing the gravity of all the views and then allocating their heights proportionally. As you can guess, the second pass doubles the time layout takes, which isn't significant for simple layouts.
Explanation of your example: The first child of the LL (the first TextView) is measured and takes a certain amount of pixels. Then your ListView takes all the remaining space (via match_parent). And then your second TextView is not drawn at all as it's off the bottom of the screen. Which is pretty much what you observed, but now you understand why.
Solution: Use RelativeLayout. Works perfectly in this case.
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="#+id/top_tv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:textSize="30sp"
android:text="Top TextView" />
<TextView
android:id="#+id/bottom_tv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:textSize="30sp"
android:text="Bottom TextView" />
<ListView
android:id="#+id/listView_Species"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#id/top_tv"
android:layout_above="#id/bottom_tv"
/>
</RelativeLayout>
The RelativeLayout tells the layout inflater to draw the first TextView at the top, then draw the second TextView at the bottom, and then fill the rest of the space with your ListView. I believe this is exactly what you want.
Welcome to Android. You'll be using this pattern a LOT!

Change the ListView height to 0dp and add weight=1
i.e.:
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="30sp"
android:text="Top TextView" />
<ListView
android:id="#+id/listView_Species"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="30sp"
android:text="Bottom TextView" />

use android:layout_weight to define weights to your widgets inside the outermost layout. Declare their height as 0dp and then define android:layout_weight to each one of them .
Total weigh sum of the three of them should be 1. According to your need you can deine 0.1 weight to both top and bottom TextView's and define 0.8 to ListView.
<TextView
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight = "0.1"
android:textSize="30sp"
android:text="Top TextView" />
<ListView
android:id="#+id/listView_Species"
android:layout_width="match_parent"
android:layout_weight = "0.8"
android:layout_height="0dp" />
<TextView
android:layout_width="match_parent"
android:layout_height="0dp"
android:textSize="30sp"
android:layout_weight = "0.1"
android:text="Bottom TextView" />

Making a View occupy a fixed width in Android layout

I have this as part of my layout:
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="0dip"
android:orientation="horizontal"
android:layout_weight="0.15">
<TextView
android:id="#+id/question_text"
android:layout_width="0dip"
android:layout_height="fill_parent" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right"
android:text="#string/score_label" />
<TextView
android:id="#+id/score_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right" />
</LinearLayout>
The first TextView is empty at the beginning of the application. Its content is changed dynamically. This makes it occupy zero space so that the second TextView is aligned to the left, even though its layout_gravity is set to right.
How can I make it occupy a fixed width, without taking the contents into account?
I thought about using layout_weight, but I know the recommendation is against using nested weights (the parent ViewGroup has a layout_weight attribute). Maybe I should use a RelativeLayout?
Thanks for any suggestions.

I solved a similar problem using the attribute android:ems="<some number>" on the TextView. An "ems" is the width of the character "M". This attribute makes the TextView exactly the given no. of ems wide.
http://developer.android.com/reference/android/widget/TextView.html

You have all of your TextViews width set to android:layout_width="wrap_content" which means that if there's nothing in there it will have no width. You need to set that to either "match_parent" which will make it the same width as it's parent container or set it to a fixed value, something like android:layout_width="100dp".