安卓自制的计算器

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。

先上一波运行图

下面是XML文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/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-->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/result"
            android:gravity="end"
            android:textSize="40sp"
            android:text="@string/zero"/>
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:orientation="horizontal"
        android:layout_weight="1">

        <Button
            android: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"/>

        <Button
            android: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/-->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">
        <Button
            android: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"/>
        <Button
            android: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"/>
        <Button
            android: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"/>
        <Button
            android: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*-->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">
        <Button
            android: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"/>
        <Button
            android: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"/>
        <Button
            android: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"/>
        <Button
            android: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- -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">

        <Button
            android: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"/>
        <Button
            android: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"/>
        <Button
            android: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"/>
        <Button
            android: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.=+-->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">

        <Button
            android: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"/>
        <Button
            android: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"/>
        <Button
            android: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"/>
        <Button
            android: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"/>

    </LinearLayout>



    <LinearLayout
        android:layout_weight="4"
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="0dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="20sp"
            android:text="@string/string1"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/string2"
            android:textSize="20sp"/>

    </LinearLayout>



</LinearLayout>

下面上活动的代码

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;



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



    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.btn0:
                if(isCheckEqu){
                    textView_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(isCheckEqu){
                    textView_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(isCheckEqu){
                    textView_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(isCheckEqu){
                    textView_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(isCheckEqu){
                    textView_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(isCheckEqu){
                    textView_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(isCheckEqu){
                    textView_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(isCheckEqu){
                    textView_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(isCheckEqu){
                    textView_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(isCheckEqu){
                    textView_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 (hasOp){
                    doEqual();//显示出来当前的答案
                }
                String myStringAdd = textView_result.getText().toString();
                if(myStringAdd.equals(null)){
                    return;
                }
                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 (hasOp){
                    doEqual();
                }
                String myStringSub = textView_result.getText().toString();
                if(myStringSub.equals(null)){
                    return;
                }
                num1 = Double.valueOf(myStringSub);
                textView_result.setText(null);
                op = 2;
                isCheckEqu = false;
                hasDec = false;
                hasOp = true;
                break;
            case R.id.btn12:
                if (hasOp){
                    doEqual();
                }
                String myStringMul = textView_result.getText().toString();
                if(myStringMul.equals(null)){
                    return;
                }
                num1 = Double.valueOf(myStringMul);
                textView_result.setText(null);
                op = 3;
                isCheckEqu = false;
                hasDec = false;
                hasOp = true;
                break;
            case R.id.btn13:
                if (hasOp){
                    doEqual();
                }
                String myStringDiv = textView_result.getText().toString();
                if(myStringDiv.equals(null)){
                    return;
                }
                num1 = Double.valueOf(myStringDiv);
                textView_result.setText(null);
                op = 4;
                hasDec = false;
                isCheckEqu = false;
                hasOp = true;
                break;

            case R.id.btn14:
                if(isCheckEqu){
                    textView_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() {
                        @Override
                        public 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();
                try {
                    textView_result.setText(myString.substring(0,myString.length()-1));
                }catch (Exception e){
                    textView_result.setText("0");
                }
                break;
            case R.id.clear:
                textView_result.setText("0");
                break;
            default:
                break;

        }
    }

    /**
     * 按下等于
     */
    private void doEqual(){
        String myStringEqu=textView_result.getText().toString();
        if(myStringEqu.equals(null))
        {
            return;
        }
        num2=Double.valueOf(myStringEqu);
        textView_result.setText(null);
        switch (op) {
            case 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;
    }
}