I am a beginner when it comes to Android developing and I am trying to write a search application that takes in a string and outputs the text messages that contain that string. My problem is with trying to format the text output on the second screen. I have the text displaying correctly using the code:
TextView textView = new TextView(this);
textView.setTextSize(20);
// Set the text view as the activity layout
setContentView(textView);
..... (find string matches)
textView.append(msg);
However, when I go and edit the .xml file for that file nothing changes (I have tried adding bold, adding a starting text etc.). I copied my TextView xml block to my activity_main.xml and it displayed a bold "hello world" on the first screen and not the second even when the TextView section was an exact copy. What is it that I am missing in the second that I am doing in the first? Is my problem in my TextView declaration? My end goal is to display many text message matches and force them to fit on the screen horizontally and allow the user to scroll vertically, is changing the second xml file the wrong way to do it?
Thanks
It appears you're mixing up the two different ways to 'create' views:
declaring them in xml and inflating them
instantiating them programmatically
The first approach is where you use an xml file to (statically) declare the layout. I.e. your layout file may be named activity_layout.xml and include the following entry that defines a TextView with id textview1.
<TextView android:id="#+id/textview1" ... />
In order to use a view in such a layout definition, you need to 'inflate' it. A common place for this is in an Activity. However, you first need to tell Android what layout to inflate from:
// inflate from 'activity_layout.xml'
setContentView(R.layout.activity_layout);
// inflate the TextView with id 'textview1'
TextView textview = (TextView) findViewById(R.id.textview1);
Now, the second approach is to (dynamically) instantiate views in code. This does not require a layout file. Typically you'll be able to differentiate this from inflating because the presence of the 'new' keyword. I.e.
// not xml definition required; all code
TextView textview = new TextView(getActivity());
I hope you're seeing where this is going? Your code snippet suggest you're using the second approach, while your explanation mentions you're modifying a layout file in the hope to see changes. Basically you're changing a layout file you're not currently using, hence you don't see anything happen.
Either change your code to use the views in the layout, or get rid of the layout and do everything in code. Usually the first approach is a more flexible one and easier to use; e.g. you'll be able to benefit from previews in Eclipse and it'll be much easier to manage if the layout gets more complex.
Your problem is this:
// Set the text view as the activity layout
setContentView(textView);
If you set setContentView like this , no matter how you change your xml file you still get the same thing. A text with size 20.
Try to create a new layout and add the Textview on it.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="#+id/TextView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1" />
</LinearLayout>
Change your code as follow:
setContentView(R.layout.new_layout);
TextView textView = (TextView)findViewById(R.id.TextView1);
..... (find string matches)
textView.append(msg);
Related
I have this GridAdapter that shows my working GridView of at least 100+ buttons, but all of these will need to navigate to a page once clicked. I'm unsure of how to begin or if what I have is a substantial place to start. I know where I'd put an OnClick method and listener but I am unsure of how to ensure every button in the grid is heard separately since they don't have Ids. Guides online have been helpful but I'm still lost. If anyone has some advice as to how to proceed I'd be grateful. Both java files are attached but the array of images is not included in the Adapter screenshot.
Grid_Adapter
Grid_Fragment
You could add android:onClick="[method name here]" within the ImageButtons in your XML layout code, to call the code when each button is clicked. Note that this method has to be public and exist within the current activity.
As an example:
<?xml version="1.0" encoding="utf-8"?>
<!-- truncated -->
<Button android:id="#+id/myButton1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button 1"
android:onClick="buttonClickMethod1" />
<!-- truncated -->
Also note that this isn't the preferred method, and that using onClick listeners or data bindings is a better approach.
Finally, I would question your activity layout of having 100+ buttons from a user perspective - that seems very high.
I am using a ViewFlipper to display all the measurements the app has made (1 measurement = 1 page element). The problem is, the performance of initializing/reloading of the content of the ViewFlipper gets very bad if there are more then 50 elements. i.e., the app gets unresponsive for about 15 seconds after it has launched. I did some logging and found out, that more than 70% of the loading time is spent on View.inflate(ctx, R.layout.view_measurement, null);
From my understanding, inflate(...) does parse the layout xml file to a View so it can be used in Java. Since the layout xml file is everytime the same, it looks to me like there is the same heavy job being done for each element over and over again. I tried many things to change this and let this happen only one time, unfortunately without success. I also tried to use and tags in the xml also but always got errors.
I know that there are better ways rather than the ViewFlipper to do this job, but as I am in a hurry everything else works fine, I would like to keep this and find a fast solution.
MainActivity.java
...
ViewFlipper viewFlipper;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
viewFlipper = (ViewFlipper)super.findViewById(R.id.measurementsViewFlipper);
int measurementsAmount = 100; //example
for(i=0; i<measurementsAmount; i++){
View measurementView = View.inflate(ctx, R.layout.view_measurement, null);
... fill the view ...
viewFlipper.add(measurementView);
}
...
}
view_measurement.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center_vertical"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:orientation="horizontal">
...
</LinearLayout>
</RelativeLayout>
The only way to reduce the xml inflation time is to reduce the number of views used in the xml layout. For example, just by looking at he layout you posted, you could(and should) remove the root RelativeLayout if it's just wrapping the LinearLayout. Also, using ConstraintLayout might allow you further remove ViewGroups and reduce the nesting level and the view count.
But this will still not be ok because the real problem is you are inflating a lot of views upfront. In your example if the page layout contains just 5 views you'll create 500 views in total(100 x 5). That's a lot and this is why you need to have a view recycle mechanism so you don't need to create all views upfront, just a few for the current pages.
If you want ViewFlipper's behavior, the Android SDK has a component called AdapterViewFlipper which you should use instead. It just needs an additional adapter class, to which you'll pass the measurement data and in which you'll inflate the measurement layout.
I've been searching the internet for a solution to this problem for several hours now and I can't seem to find an answer that works.
I have written an android app that uses the camera emulator in Eclipse to take a photo and save it to the sd card (path is stored using a String called "file"). What I would like to do is display the image, preferably in a sort of pop-out window, with another button that closes it and returns to the app. I expect I'll need to create another class to do this, but I am not sure all that is involved. Will I have to create another XML file to do the layout? How could I access the file and display it? I expect I'll use ImageView if I am to use another class, but other than that I'm not sure what to do.
There's not much code I can really provide that would help, other than the method which is called when the button is clicked. This part of the code works just fine, and it's simply a method that looks like this:
public void viewPhoto(file){ }
As you can see, I have nothing inside the method yet, that is why I am posting here.
I have been trying to figure this out for several hours, so I would greatly appreciate any ideas you folks might have.
EDIT: MORE INFO
Many of the suggestions I have found require the image to be stored in the "src" folder of the project. However, this photo will be taken and used all within the same program, so I'll have to be able to access it using its file path alone. I can't just state its location in the XML. I created a Dialog object within my existing code, but I'm not sure if this will work. The dialog I plan to use should be able to access the photo from the specified path that is stored in the string mentioned before.
I have been referring to the first answer in this thread: Android Image Dialog/Popup
but as you can see it requires the image to be in the src folder and specified in the XML.
SECOND EDIT:
Here is the code I currently have, both for the XML and the Java. But first I want to mention that I have two XML files--one called activity_main.xml which handles all the initial buttons, menu, etc. The second one is only for my photo (called photo_viewer.xml) and it only contains the ImageView.
photo_viewer.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pictureViewer"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<ImageView
android:id="#+id/imageView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:contentDescription="#string/viewImage" />
</RelativeLayout>
Java method to generate image:
public void viewPhoto(String file){
ImageView imageView = new ImageView(getApplicationContext());
LayoutParams lp = new LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT);
Bitmap image = BitmapFactory.decodeFile(file);
imageView.setImageBitmap(image);
RelativeLayout rl = (RelativeLayout)findViewById(R.id.pictureViewer);
rl.addView(imageView, lp);
}
you need to create a class which would extend Dialog Class.
refer this how you can create your own dialog.
How to create a Custom Dialog box in android?
then for showing image just call DialogObj.show() to show dialog.
I have created a TextView in the UI designer, but I can't figure out how I should access it from the code. I have tried Go To Declaration but that just brings me to the XML file where the TextView is 'made'. Does anyone know how to do this? Help is very much appreciated!
This is independent of the IDE. First you need to "find" the TextView, then you can modify its properties:
TextView myTextView = (TextView) findViewById(R.id.yourid); // The ID is declared in the XML file as android:id atrribute.
myTextView.setText("New Text");
What do you mean by "access it from the code"? If you're talking about navigating from where it's referenced in the code to viewing it in the UI designer, newer versions of Intellij with Android support enabled put tabs at the bottom of the editor when you're editing XML files to let you switch between a text representation and a visual representation of layout files.
If you're talking about how to instantiate the view in code, post some samples of what you've been trying (the most common way is to use a LayoutInflater).
Edit:
Changing the actual text that's displayed in the TextView isn't an IDE-specific issue. You have two ways to do this (well, three if you count the visual and text views of the XML file as separate methods). You can set the text either in the XML file by setting the android:text attribute on the TextView widget, or in the code by calling setText(). Whichever way you decide to do it, you should consider not referring to your text as a raw string but as a String resource as described here.
Edit 2:
OK, you're looking for instructions on how to inflate the view in the first place to get access to it. This is what I answered initially, but here's a little more code. In your Activity (you do have an Activity set up, right?):
LayoutInflater inflater = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.<your layout ID>, null);
RelativeLayout item = (RelativeLayout) view.findViewById(R.id.<your TextView's id>);
I have an android project that has several small views which I need to instantiate at runtime. I haven't been able to figure out a way to store all of these related views in a single xml file and I now there are going to be many of these xml files. I was just wondering if there is any way to have them all in a single file, but not belonging to some parent ViewGroup.
The layout folder in android kinda sucks since there's no way to make subfolders, everything is just piled into the same place, ugh.
I hope someone can tell me of a better way of organizing these things.
If I understand you correctly you want several views meged onto one screen or merged into one xml file. You can include other xml's into one.
The articles showed you how to use the tag in XML layouts,
to reuse and share your layout code. This article explains the tag and how it complements the tag.
http://developer.android.com/resources/articles/layout-tricks-merge.html
Also, this video might help (about 19 minutes in). Shows you how to extract a current layout and be able to include it in others.
a couple things:
Yes, the layout folder is a pain. I use strict naming conventions to make it bearable, and in eclipse use the shortcut ctrl + shift + r to quickly find the layout I am looking for. Try naming your layouts after your activity: activity1_menu_overlay and activity1_main. With the above shortcut, just type out Activity1 and it will only show you the relevant layouts.
And if that doesn't work, you can try wrapping all your views in LinearLayouts and using view.setVisibility(View.Gone); or view.setVisibility(View.Visible); to show/hide the appropriate views.
Here is an example of that second one, because it's tough to explain.
one XML file:
<LinearLayout>
<LinearLayout ... android:visibility="visible">
<copy/paste of view 1>
</Linearlayout>
<Linearlayout ... android:visibility="gone">
<copy/paste of view 2>
</Linearlayout>
<Linearlayout ... android:visibility="gone">
<copy/paste of view 3>
</Linearlayout>
<Linearlayout ... android:visibility="gone">
<copy/paste of view etc.>
</Linearlayout>
</Linearlayout>
keep in mind this approach will require you to define a reference to each "child" LinearLayout view in your activity, so you can call setVisiblity appropriately.
This approach works well for animations, and I would only use it for 2 or 3 possible views in one xml file.