how to operate on data recorded from edit text

Question

I want to take the depth input by the user and mathematically operate on it to obtain cost and then display it to the user. How do I go about doing that?(If didn't notice already, I don't know Java). Thanks.

 private void estimateCost(View view){
        EditText depth = findViewById(R.id.depth);
        TextView cost = findViewById(R.id.cost);
        String x = depth.getText().toString().trim();
        cost.setText(x);
    }

It is in string, so I can't use any mathematical operations on it. Is there any way to convert it to int? — Ajay Bhargav, Nov 08 '17 at 15:52

canihazurcode · Answer 1 · 2017-11-08T16:33:49.060

2

You need to parse your String obtained from EditText, then perform some operations.

 private void estimateCost(View view){
    EditText depth = findViewById(R.id.depth);
    TextView cost = findViewById(R.id.cost);

    String x = depth.getText().toString().trim();  

    // parse to a number, i.e. int
    int depthValue = Integer.parseInt(x);

    // calculate total cost
    int totalCost = ...

    cost.setText(String.valueOf(totalCost));
}

edited Nov 08 '17 at 16:33

answered Nov 08 '17 at 15:53

canihazurcode

252
2
9

app keeps crashing – Ajay Bhargav Nov 08 '17 at 16:04
You actually forget to convert totalCost back to string – Rainmaker Nov 08 '17 at 16:30

gbruscatto · Accepted Answer · 2017-11-08T18:45:15.243

0

You can create a button to obtain the value. For example:

<Button
        android:id="@+id/bt_calc"
        android:text="calc"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

Then you can catch the click event (put it inside onCreate method):

EditText depth = (EditText) findViewById(R.id.depth);
TextView cost = (TextView) findViewById(R.id.cost);
Button btCalc = (Button) findViewById(R.id.bt_calc);
int costValue;

btCalc.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //in here you can

            //get the depth from the EditText:
            int depthValue = Integer.valueOf(depth.getText().toString());

            //do the operations (example):
            costValue = depthValue + 1;

            //and display the cost in the TextView:
            cost.setText(String.valueOf(costValue));
        }
});

Good luck!

edited Nov 08 '17 at 18:45

answered Nov 08 '17 at 15:57

gbruscatto

686
7
21

Where did you put the code? You need to put it inside a method (onCreate for example). – gbruscatto Nov 08 '17 at 17:53
Also, you need to create the button inside your layout, like in the example. – gbruscatto Nov 08 '17 at 17:57
LOL. You are a little late on the update buddy. On both the things, in fact. Figured it out from some place else. Thanks anyway for at least remembering to put a comment. – Ajay Bhargav Nov 08 '17 at 18:18
So, I need to put all the code related to user input inside the *onCreate()* ? – Ajay Bhargav Nov 08 '17 at 18:20
Yes. Or you can put it inside another method and call it from onCreate(). – gbruscatto Nov 08 '17 at 18:32

score 0 · Answer 3 · answered Nov 08 '17 at 15:58

0

If your input contains letters as well you won't get int from it with Integer.parseInt()

Use this

int x = 0;
for (int i=0; i < str.length(); i++) {
    char c = s.charAt(i);
    if (c < '0' || c > '9') continue;
    x = x * 10 + c - '0';
}

answered Nov 08 '17 at 15:58

Rainmaker

10,294
9
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how to operate on data recorded from edit text

3 Answers3