Src com.exceple.lilin MainActivity.java package com.example.lilin; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; public class MainActivity extends Activity { /** Called when the activity is first created. */ private Button button1=null; private Button button2=null; private Button button3=null; private Button button4=null; private Button button5=null; private Button button6=null; private Button button7=null; private Button button8=null; private Button button9=null; private Button button0=null; private Button buttonAdd=null; private Button buttonMinus=null; private Button buttonClear=null; private Button buttonMultiple=null; private Button buttonDiv=null; private Button buttonResult=null; private EditText et=null; String a=""; int symbol; double x; double y; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.fragment_main); button0=(Button)findViewById(R.id.button_0); button1=(Button)findViewById(R.id.button_1); button2=(Button)findViewById(R.id.button_2); button3=(Button)findViewById(R.id.button_3); button4=(Button)findViewById(R.id.button_4); button5=(Button)findViewById(R.id.button_5); button6=(Button)findViewById(R.id.button_6); button7=(Button)findViewById(R.id.button_7); button8=(Button)findViewById(R.id.button_8); button9=(Button)findViewById(R.id.button_9); buttonAdd=(Button)findViewById(R.id.button_add); buttonMinus=(Button)findViewById(R.id.button_minus); buttonClear=(Button)findViewById(R.id.button_clear); buttonMultiple=(Button)findViewById(R.id.button_multiple); buttonDiv=(Button)findViewById(R.id.button_div); buttonResult=(Button)findViewById(R.id.button_result); et=(EditText)findViewById(R.id.result_text); button0.setOnClickListener...
