这是本人自己用安卓编写的计算器，代码的优化可能有所问题，不过大家都在学习阶段，欢迎大家批评指正，还是上源码吧。

先来运行图package com.example.nanchen.exam_1_1;import android.content.DialogInterface;import android.support.v7.app.AlertDialog;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.TextView;public class MainActivity extends AppCompatActivity implements View.OnClickListener{private Button btn0;private Button btn1;private Button btn2;private Button btn3;private Button btn4;private Button btn5;private Button btn6;private Button btn7;private Button btn8;private Button btn9;private Button btnAdd;private Button btnSub;private Button btnMul;private Button btnDiv;private Button btnDec;private Button btnEqual;private Button btnClear;private Button btnBackSpace;private TextView textView_result;double num1 = 0,num2 = 0,result = 0;//定义存储结果和两个操作数boolean isCheckEqu = false;//检测是否点击了等于int op = 0;//定义运算符boolean hasDec = false;boolean hasOp = false;@Overrideprotected void onCreate Bundle savedInstanceStatesuper.onCreate savedInstanceState;setContentView yout.activity_main;textView_result = TextView findViewById R.id.result;btn0 = Button findViewById R.id.btn0;btn1 = Button findViewById R.id.btn1;btn2 = Button findViewById R.id.btn2;btn3 = Button findViewById R.id.btn3;btn4 = Button findViewById R.id.btn4;btn5 = Button findViewById R.id.btn5;btn6 = Button findViewById R.id.btn6;btn7 = Button findViewById R.id.btn7;btn8 = Button findViewById R.id.btn8;btn9 = Button findViewById R.id.btn9;btnAdd = Button findViewById R.id.btn10;btnSub = Button findViewById R.id.btn11;btnMul = Button findViewById R.id.btn12;btnDiv = Button findViewById R.id.btn13;btnDec = Button findViewById R.id.btn14;btnEqual = Button findViewById R.id.btn15;btnClear = Button findViewById R.id.clear;btnBackSpace = Button findViewById R.id.backSpace;btn0.setOnClickListener this;btn1.setOnClickListener this;btn2.setOnClickListener this;btn3.setOnClickListener this;btn4.setOnClickListener this;btn5.setOnClickListener this;btn6.setOnClickListener this;btn7.setOnClickListener this;btn8.setOnClickListener this;btn9.setOnClickListener this;btnAdd.setOnClickListener this;btnSub.setOnClickListener this;btnDec.setOnClickListener this;btnDiv.setOnClickListener this;btnEqual.setOnClickListener this;btnMul.setOnClickListener this;btnClear.setOnClickListener this;btnBackSpace.setOnClickListener this;@Overridepublic void onClick View vswitch v.getIdcase R.id.btn0:if isCheckEqutextView_result.setText null;isCheckEqu=false;String myString0 =textView_result.getText.toString;if myString0.equals"0"myString0 = "";myString0 += "0";textView_result.setText myString0;break;case R.id.btn1:if isCheckEqutextView_result.setText null;isCheckEqu=false;String myString1 =textView_result.getText.toString;if myString1.equals"0"myString1 = "";myString1 += "1";textView_result.setText myString1;break;case R.id.btn2:if isCheckEqutextView_result.setText null;isCheckEqu=false;String myString2 =textView_result.getText.toString;if myString2.equals"0"myString2 = "";myString2 += "2";textView_result.setText myString2;break;case R.id.btn3:if isCheckEqutextView_result.setText null;isCheckEqu=false;String myString3 =textView_result.getText.toString;if myString3.equals"0"myString3 = "";myString3 += "3";textView_result.setText myString3;break;case R.id.btn4:if isCheckEqutextView_result.setText null;isCheckEqu=false;String myString4 =textView_result.getText.toString;if myString4.equals"0"myString4 = "";myString4 += "4";textView_result.setText myString4;break;case R.id.btn5:if isCheckEqutextView_result.setText null;isCheckEqu=false;String myString5 =textView_result.getText.toString;if myString5.equals"0"myString5 = "";myString5 += "5";textView_result.setText myString5;break;case R.id.btn6:if isCheckEqutextView_result.setText null;isCheckEqu=false;String myString6 =textView_result.getText.toString;if myString6.equals"0"myString6 = "";myString6 += "6";textView_result.setText myString6;break;case R.id.btn7:if isCheckEqutextView_result.setText null;isCheckEqu=false;String myString7 =textView_result.getText.toString;if myString7.equals"0"myString7 = "";myString7 += "7";textView_result.setText myString7;break;case R.id.btn8:if isCheckEqutextView_result.setText null;isCheckEqu=false;String myString8 =textView_result.getText.toString;if myString8.equals"0"myString8 = "";myString8 += "8";textView_result.setText myString8;break;case R.id.btn9:if isCheckEqutextView_result.setText null;isCheckEqu=false;String myString9 =textView_result.getText.toString;if myString9.equals"0"myString9 = "";myString9 += "9";textView_result.setText myString9;break;case R.id.btn10:if hasOpdoEqual;//显示出来当前的答案String myStringAdd =textView_result.getText.toString;if myStringAdd.equals nullreturn;num1 = Double.valueOf myStringAdd;textView_result.setText null;// 这里被清除了op = 1;isCheckEqu = false;hasDec = false;hasOp = true;break;case R.id.btn11:if hasOpdoEqual;String myStringSub =textView_result.getText.toString;if myStringSub.equals nullreturn;num1 = Double.valueOf myStringSub;textView_result.setText null;op = 2;isCheckEqu = false;hasDec = false;hasOp = true;break;case R.id.btn12:if hasOpdoEqual;String myStringMul =textView_result.getText.toString;if myStringMul.equals nullreturn;num1 = Double.valueOf myStringMul;textView_result.setText null;op = 3;isCheckEqu = false;hasDec = false;hasOp = true;break;case R.id.btn13:if hasOpdoEqual;String myStringDiv =textView_result.getText.toString;if myStringDiv.equals nullreturn;num1 = Double.valueOf myStringDiv;textView_result.setText null;op = 4;hasDec = false;isCheckEqu = false;hasOp = true;break;case R.id.btn14:if isCheckEqutextView_result.setText null;isCheckEqu=false;if hasDec//如果已经有小数点了,则弹出一个对话框AlertDialog.Builder builder = new AlertDialog.Builder MainActivity.this;builder.setTitle"警告";builder.setMessage"输入错误，一个数字不能有两个小数点！";builder.setNegativeButton"取消", new DialogInterface.OnClickListener@Overridepublic void onClick DialogInterface dialog, int which;builder.show;return;hasDec = true;String myString14 =textView_result.getText.toString;myString14 += ".";textView_result.setText myString14;break;case R.id.btn15:doEqual;hasOp = false;break;case R.id.backSpace:String myString =textView_result.getText.toString;trytextView_result.setText myString.substring0,myString.length -1;catch Exception etextView_result.setText"0";break;case R.id.clear:textView_result.setText"0";break;default:break;/*** 按下等于*/private void doEqualStringmyStringEqu=textView_result.getText.toString;if myStringEqu.equals nullreturn;num2=Double.valueOf myStringEqu;textView_result.setText null;switch opcase 0:result=num2;break;case 1:result=num1+num2;break;case 2:result=num1-num2;break;case 3:result=num1*num2;break;case 4:result=num1/num2;break;default:result=0;break;textView_result.setText String.valueOf result;isCheckEqu=true;<?xml version="1.0" encoding="utf-8"?>LinearLayoutxmlns:android="/apk/res/android"xmlns:tools="/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"tools:context="com.example.nanchen.exam_1_1.MainActivity"<!--显示结果-->LinearLayoutandroid:layout_width="match_parent"android:layout_height="0dp"android:layout_weight="1"TextViewandroid:layout_width="match_parent"android:layout_height="match_parent"android:id="@+id/result"android:gravity="end"android:textSize="40sp"android:text="@string/zero"LinearLayoutLinearLayoutandroid:layout_width="match_parent"android:layout_height="0dp"android:orientation="horizontal"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:layout_weight="1"android:layout_height="wrap_content"android:text="@string/clear"android:id="@+id/clear"android:textAllCaps="false"android:gravity="center"android:textSize="25sp"Buttonandroid:layout_width="0dp"android:layout_weight="1"android:layout_height="wrap_content"android:text="@string/backspace"android:id="@+id/backSpace"android:textAllCaps="false"android:gravity="center"android:textSize="25sp" LinearLayout<!--789/-->LinearLayoutandroid:layout_width="match_parent"android:layout_height="0dp"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/seven"android:id="@+id/btn7"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/eight"android:id="@+id/btn8"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/nine"android:id="@+id/btn9"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/del"android:id="@+id/btn13"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1" LinearLayout<!--456*-->LinearLayoutandroid:layout_width="match_parent"android:layout_height="0dp"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/four"android:id="@+id/btn4"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/five"android:id="@+id/btn5"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/six"android:id="@+id/btn6"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/mul"android:id="@+id/btn12"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1" LinearLayout<!--123- -->LinearLayoutandroid:layout_width="match_parent"android:layout_height="0dp"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/one"android:textSize="30sp"android:id="@+id/btn1"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/two"android:id="@+id/btn2"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/three"android:id="@+id/btn3"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/sub"android:id="@+id/btn11"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1" LinearLayout<!--0.=+-->LinearLayoutandroid:layout_width="match_parent"android:layout_height="0dp"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/zero1"android:id="@+id/btn0"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/dec"android:id="@+id/btn14"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/equal"android:id="@+id/btn15"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"Buttonandroid:layout_width="0dp"android:text="@string/add"android:id="@+id/btn10"android:textSize="30sp"android:gravity="center"android:layout_height="wrap_content"android:layout_weight="1"LinearLayoutLinearLayoutandroid:layout_weight="4"android:orientation="vertical"android:layout_width="match_parent"android:layout_height="0dp"TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:textSize="20sp"android:text="@string/string1"TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:text="@string/string2"android:textSize="20sp"LinearLayoutLinearLayout。