Android calculator app frontend: How to allow number inputs using buttons instead of keyboard?

Question

We all know how calculator works. I am trying to make a calculator in android studio. The thing is I don't want the user to use their keyboard to give number inputs, instead the user is gonna use the buttons on the app. The picture shown below-

Now the question is how to do this button thing? When user clicks button 1 the edittext should show 1, if pressed 2 then show 2 after the 1 in edittext. I am not having any idea at all. I just want an equation in the edittext like 456+54-56/5 like this. I can probably do the math coding but I can't have the numbers. And I don't know how to take input in the edittext other than the keyboard which is not really a calculator thing.

I couldn't try anything. I kinda did this-

Button C_button = findViewById(R.id.c);
        C_button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                ((EditText)findViewById(R.id.et_ans)).setText("0");
            }
        });

But I know why it doesn't work, it just simply put the string zero all together in the edittext every time I click the zero button. But not working like the keyboard entry. Can somebody help me with this?

Answer 1

You can fetch the string that is already present in the EditText and then concatenate the new number present.

Ex: -

EditText edt = ((EditText)findViewById(R.id.et_ans));
Button one_button = findViewById(R.id.one);
     one_button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                  String a=edt.getText().toString();
                  edt.setText(a+ "1");
                }
            });