CODEWITHSUNDEEP
androidbuttonandroid-button
asepdf
asepdf

Reputation: 13

Android calculator buttons

I am trying to make a calculator for Android. Here is the code for my buttons:

int[] button_ids = {
    R.id.BtnNum0, R.id.BtnNum1, R.id.BtnNum2, R.id.BtnNum3, R.id.BtnNum4, R.id.BtnNum5, R.id.BtnNum6,
    R.id.BtnNum7, R.id.BtnNum8, R.id.BtnNum9, R.id.BtnAdd, R.id.BtnSub, R.id.BtnDiv, R.id.BtnMult,
    R.id.BtnClear, R.id.equals
};


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    EditTextValue = (EditText) findViewById(R.id.editText1);
    TVValue = (TextView) findViewById(R.id.textView1);      
    buttons = new ArrayList<Button>();

    for(int id : button_ids) {
        Button button = (Button)findViewById(id);
        button.setOnClickListener(this);
        buttons.add(button);
    }   

}

How I can change this part to a block of code where I won't have to declare the IDs of the buttons? (e.g. R.id.BtnNum0)

int[] button_ids = {
    R.id.BtnNum0, R.id.BtnNum1, R.id.BtnNum2, R.id.BtnNum3, R.id.BtnNum4, R.id.BtnNum5, R.id.BtnNum6,
    R.id.BtnNum7, R.id.BtnNum8, R.id.BtnNum9, R.id.BtnAdd, R.id.BtnSub, R.id.BtnDiv, R.id.BtnMult,
    R.id.BtnClear, R.id.equals
};

I have been searching for an answer, but I still can't find a solution.

Upvotes: 0

Views: 1224

Answers (4)

codeMagic
codeMagic

Reputation: 44571

What you can do, since this code seems to only set a single OnClickListener for all Buttons, is to do it in xml

For each Button set

android:onClick="functionName"

then in your code you can do away with all of the id's and your for loop. In Java just create a function like

public void functionName(View v)
{
    switch (v.getId())
    {
        case R.id.buttonId:
        // do work for this Button
         break;
       ...
}

The way you are doing it is fine but this is how I prefer to handle this situation. You just have to give all of the Buttons the same function name in xml then use that name as your function name in Java. You also just have to be sure to declare the function with a void return type and make sure it takes a View as its one and only parameter as in my example.

The Button Docs also have an example of this

Upvotes: 1

Paul Lammertsma
Paul Lammertsma

Reputation: 38272

As trevor-e suggested, you can give an annotation processor a try. Android Annotations can simplify your code to:

@Click
public void BtnNum0() {
    // Button 0 clicked
}
@Click
public void BtnNum1() {
    // Button 1 clicked
}
// etc.

If you go this route, please do try to use names following the Java convention as the button names correspond with function names.

Upvotes: 0

Onur A.
Onur A.

Reputation: 3017

in your layout file add this to every button

 <Button
   ...
   android:onClick="btnClicked"
   .../>

then in your code add this method and check for each button in this method

public void btnClicked(View v)
{
   switch(v.getId())
   {
      case R.id.BtnNum0:
      // your code
      break;
      ....
   }
}

Upvotes: 1

telkins
telkins

Reputation: 10550

That is likely the best solution unfortunately, unless you use some sort of annotation framework which still doesn't cut down much on the boilerplate.

edit:

You could try to get a pointer to whatever ViewGroup is holding the Button views and then getting all of its children, and then looping through them while casting them to Buttons as you go.

For example: If your Button objects in XML are housed in a LinearLayout, you could get the pointer to that and do something like this: 

for(int i=0; i < ((ViewGroup)v).getChildCount(); ++i) {
    Button nextChild = (Button) ((ViewGroup)v).getChildAt(i);
}

Of course, I recommend against this, but it is still a possibility.

Upvotes: 0

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