How to write the code of a simple calculator realized by Android

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Activity_main.xml

Arrays.xml

Please select the operator +-* /

MainActivity

Package com.jld.homework; import android.os.Bundle;import android.view.View;import android.widget.AdapterView;import android.widget.Button;import android.widget.EditText;import android.widget.Spinner;import android.widget.TextView; import androidx.appcompat.app.AppCompatActivity; public class MainActivity extends AppCompatActivity {String op; @ Overrideprotected void onCreate (Bundle savedInstanceState) {super.onCreate (savedInstanceState); setContentView (R.layout.activity_main); Spinner spinner = (Spinner) this.findViewById (R.id.operator) / / get the Spinner object in the active layout / / register the internal listener object spinner.setOnItemSelectedListener (new AdapterView.OnItemSelectedListener () {@ Overridepublic void onItemSelected (AdapterView parent, View view, int position, long id) {/ / assign the value of the Spinner option to the member variable op (save arithmetic operator) op = ((TextView) view). GetText () .toString ();} @ Overridepublic void onNothingSelected (AdapterView parent) {}) / / various components Button calcButton = findViewById (R.id.calc); EditText firstNum = findViewById (R.id.firstNum); EditText secondNum = findViewById (R.id.secondNum); TextView result = findViewById (R.id.result); / / Computing Core calcButton.setOnClickListener (v-> {switch (op) {case "+": {double r = Double.parseDouble (firstNum.getText (). ToString ()) + Double.parseDouble (secondNum.getText (). ToString ()); result.setText (String.valueOf (r)); break } case "-": {double r = Double.parseDouble (firstNum.getText (). ToString ())-Double.parseDouble (secondNum.getText (). ToString ()); result.setText (String.valueOf (r)); break;} case "*": {double r = Double.parseDouble (firstNum.getText (). ToString ()) * Double.parseDouble (secondNum.getText (). ToString ()); result.setText (String.valueOf (r)); break } case "/": {double r = Double.parseDouble (firstNum.getText (). ToString ()) / Double.parseDouble (secondNum.getText (). ToString ()); result.setText (String.valueOf (r)); break;} default:// illegal error result.setText (R.string.ERROR); break;}}) }} Thank you for your reading. The above is the content of "how to write the code for Android to implement a simple calculator". After the study of this article, I believe you have a deeper understanding of how to write the code for Android to achieve a simple calculator, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!