Java "for" loop to populate textviews

Question

There has to be a better way to do this but everything I've tried fails. Maybe I have to programtically create the textViews, I'm not sure.

I have this:

if (totalCount[0] > 0) {
    b1Pct = df.format((totalMs[0] / (float) totalTestMs) * 100);
    b1 = df.format((totalBits[0] / totalCount[0]) / 1000000);
}
if (totalCount[1] > 0) {
    b2Pct = df.format((totalMs[1] / (float) totalTestMs) * 100);
    b2 = df.format((totalBits[1] / totalCount[1]) / 1000000);
}
if (totalCount[2] > 0) {
    b3Pct = df.format((totalMs[2] / (float) totalTestMs) * 100);
    b3 = df.format((totalBits[2] / totalCount[2]) / 1000000);
}

As you can see I have need of a loop to cut this code down, it actually goes for another 6 entries. I'd like to do something like this but it doesn't work how I'd hoped:

for (var i=0; i < totalCount.length; i++) {

var count = i+1;

    if (totalCount[i] > 0) {
        "b"+count+"Pct" = df.format((totalMs[i] / (float) totalTestMs) * 100);
        "b"+count = df.format((totalBits[i] / totalCount[i]) / 1000000);
        "Bucket"+count.setText(b+count); "Bucket"+count+"pct".setText("b"+count+"Pct");
    }
}

Obviously that doesn't work.

Edit

I've cut a whole ton of lines down, so thank you. I'm sure it can still be improved?

DecimalFormat df = new DecimalFormat("0.00");

String[] percentages = { "b1Pct", "b2Pct", "b3Pct", "b4Pct", "b5Pct", "b6Pct", "b7Pct", "b8Pct", "b9Pct", "b10Pct" };
String[] mbpsResults = { "b1", "b2", "b3", "b4", "b5", "b6", "b7", "b8", "b9", "b10" };
TextView[] buckets = { Bucket1, Bucket2, Bucket3, Bucket4, Bucket5, Bucket6, Bucket7, Bucket8, Bucket9, Bucket10 };
TextView[] bucketsPct = { Bucket1pct, Bucket2pct, Bucket3pct, Bucket4pct, Bucket5pct, Bucket6pct, Bucket7pct, Bucket8pct, Bucket9pct, Bucket10pct };

for (int j = 0; j < totalCount.length; j++) {

if (totalCount[j] > 0) {
    percentages[j] = df.format((totalMs[j] / (float) totalTestMs) * 100);
    mbpsResults[j] = df.format((totalBits[j] / totalCount[j]) / 1000000);
    buckets[j].setText(mbpsResults[j]); 
    bucketsPct[j].setText(percentages[j]);
}

else {
    buckets[j].setText("0"); 
    bucketsPct[j].setText("0");
}
}

Add all of your TextViews in an ArrayList and iterate the arraylist to change the text of each TextView. — Pavlos
– Pavlos, Commented Sep 25, 2014 at 20:57

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

Yes, creating the views programmatically is one solution (and of course putting them in an array or ArrayList after doing so). You can, however, just add those items to an array afterwards.

EditText[] textBoxes = new EditText[numberOfViews];

textBoxes[0] = findViewById(R....);

textBoxes[1] = findVi...

The way to create them manually is to just make a new EditText object and setting all the parameters you would otherwise set in your xml file. For example you would

for(int i = 0; i < amount; i++) {
    textBoxes[0] = new EditText(this);
    textBoxes[0].setWidth(...);
}

Of course you'll have to add them to your parent view (the activity) afterwards.

Hope this helps!

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Sep 25, 2014 at 21:02

Yorrd

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3 Comments

Dan Over a year ago

I have updated my answer, it have cut out a lot of lines thanks to your suggestions

Dan Over a year ago

any further comments?

Yorrd Over a year ago

I think this is about as tight as it will get!

Bruno Cardoso · Accepted Answer · 2014-09-25 21:10:19Z

0

It seems pretty straight forward (if that's what you need).

Let's say you need to create 5 TextViews programatically:

int N = 5;
List<TextView> list = new ArrayList<TextView>(N);
for (int i = 0; i < N; i++) {
    TextView t = new TextView(this);
    t.setText("Textview number: " + i); //customize as you wish            
    list.add(t);
}

By the way, I saw you are doing a lot of String concatenations there. It would be much faster to use a StringBuilder to add all the characters, and then produce the final string just once with toString().

answered Sep 25, 2014 at 21:10

Bruno Cardoso

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2 Comments

Dan Over a year ago

I've updated my answer now with my new code. Any more suggestions? I wasn't clear on the StringBuilder comment

Bruno Cardoso Over a year ago

Let's see if I can clarify. Concatenating Strings like this "hello " + "world". Will make Java create a new String("hello world") for every concatenation. If you use a StringBuilder object, and just append the Characters that you need, it will only allocate a new String with the needed memory when you call the toString() method on it. This will be MUCH faster than the former method.

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