Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
2.1k views
in Technique[技术] by (71.8m points)

android: LayoutParams for TextView makes the view disappear, programmatically

I've hit this from various different angles. Basically the gist is this:

I've layed out a template in XML for an interface which NEEDS to be run programmatically, so it's going to be populated dynamically during the run.

The problem here, is that the XML TextView has quite a few layout tweaks (which work) and are necessary. But if I actually set them in code, the TextView doesn't even show up.

(The TextView, by the way, is nested inside a TableRow, thus the call to weight.) The XML template I designed first, to use as reference for the code is this, and it works just fine:

<TextView
  android:id="@+id/txtviewWhiteBox"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_weight="1.0"
  android:background="@drawable/textview_9patch_white"
  android:gravity="center"
  android:text="75"
  android:textColor="@android:color/black"
  android:layout_margin="20dp"
  android:padding="20dp"
  android:textSize="40dp" />

Like I said, that lays out perfectly. When I run the same layout in code though, and apply LayoutParams, the TextView disappears.

Here's the relevant snippet:

int textViewExampleID = 9001;

private TextView txtviewExample = new TextView(this);

private void buildTextView(){   
    LayoutParams paramsExample = new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT,1.0f);
    txtviewExample.setId(textViewExampleID);
    txtviewExample.setBackgroundResource(R.drawable.textview_9patch_white);
    txtviewExample.setGravity(Gravity.CENTER);
    txtviewExample.setTextColor(getResources().getColor(android.R.color.black));
    paramsExample.setMargins(20, 20, 20, 20);
    txtviewExample.setPadding(20, 20, 20, 20);
    txtviewExample.setTextSize(40); 
    txtviewExample.setText("customExample");

    //if I comment out the following line, this TextView displays.
    //if I leave it in, it doesn't display.
    txtviewExample.setLayoutParams(paramsExample);
}

I realize there's all sorts of available classes for LayoutParams, and I've been playing with them all LinearLayout.LayoutParams, TableView.LayoutParams, RelativeLayout.LayoutParams, LayoutParams just by itself... No matter which one I try, any attempt at calling "setLayoutParams" renders the entire TextView gone. I've scoured the forums here, and haven't quite found the answer. This can't be THAT uncommon.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

well, that was painful but I finally got it figured out. The most important thing to remember (that I just realized) is that of all the myriads of LayoutParams, you need to use the one that relates to the PARENT of the view you're working on, not the actual view.

So in my case, I was trying to get the TextView margins working, but it was being put inside a TableRow. The one simple change was ensuring that the type of LayoutParams being used were the ones for TableRow:

private void buildTextView(){   
    // the following change is what fixed it
    TableRow.LayoutParams paramsExample = new TableRow.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT,1.0f);
    txtviewExample.setId(textViewExampleID);
    txtviewExample.setBackgroundResource(R.drawable.textview_9patch_white);
    txtviewExample.setGravity(Gravity.CENTER);
    txtviewExample.setTextColor(getResources().getColor(android.R.color.black));
    paramsExample.setMargins(20, 20, 20, 20);
    txtviewExample.setPadding(20, 20, 20, 20);
    txtviewExample.setTextSize(40); 
    txtviewExample.setText("customExample");
    txtviewExample.setLayoutParams(paramsExample);
}

Thanks guys, hopefully this will come in handy for somebody else down the line, as I saw a lot of semi-related questions in the forums here, but not one that really defines the problem.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...