简易的计算器

image.png

image.png

说明：这个计算器所实现的逻辑十分简单，只是定义了cText字符串存所点击按钮的值，判断字符串中包含加减乘除四个运算符中的哪一个，接下来拆分字符串，转换成两个double类型的数进行运算。所以这个计算器一次只能进行两个数的运算，例：求1+1+2 ，需要先输入1+1，然后点=得值，再去加2，点=得值。这个计算器还有很多的地方需要完善，这是本人第一个安卓程序，希望今后学习更多东西后能逐步完善它。

布局

<?xml version="1.0" encoding="utf-8"?>
<GridLayout 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:rowCount="6"
    android:columnCount="4"
    tools:context="com.example.gaza.calculator.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_columnSpan="4"
        android:layout_marginLeft="4px"
        android:gravity="left"
        android:text=""
        android:textSize="50dip"
        android:id="@+id/textView" />
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_columnSpan="4"
        android:text="清除"
        android:textSize="26sp"
        android:id="@+id/bt_clear" />
    <Button android:text="1" android:textSize="26sp"
        android:id="@+id/bt_num1" />
    <Button android:text="2" android:textSize="26sp"
        android:id="@+id/bt_num2" />
    <Button android:text="3" android:textSize="26sp"
        android:id="@+id/bt_num3" />
    <Button android:text="+" android:textSize="26sp"
        android:id="@+id/bt_add" />
    <Button android:text="4" android:textSize="26sp"
        android:id="@+id/bt_num4" />
    <Button android:text="5" android:textSize="26sp"
        android:id="@+id/bt_num5" />
    <Button android:text="6" android:textSize="26sp"
        android:id="@+id/bt_num6" />
    <Button android:text="-" android:textSize="26sp"
        android:id="@+id/bt_reduce" />
    <Button android:text="7" android:textSize="26sp"
        android:id="@+id/bt_num7" />
    <Button android:text="8" android:textSize="26sp"
        android:id="@+id/bt_num8" />
    <Button android:text="9" android:textSize="26sp"
        android:id="@+id/bt_num9" />
    <Button android:text="*" android:textSize="26sp"
        android:id="@+id/bt_multiply" />
    <Button android:text="." android:textSize="26sp"
        android:id="@+id/bt_point" />
    <Button android:text="0" android:textSize="26sp"
        android:id="@+id/bt_num0" />
    <Button android:text="=" android:textSize="26sp"
        android:id="@+id/bt_result" />
    <Button android:text="/" android:textSize="26sp"
        android:id="@+id/bt_divide" />
</GridLayout>

MainActivity.java

package com.example.gaza.calculator;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity implements OnClickListener {

    private Button bt_num1;
    private Button bt_num2;
    private Button bt_num3;
    private Button bt_num4;
    private Button bt_num5;
    private Button bt_num6;
    private Button bt_num7;
    private Button bt_num8;
    private Button bt_num9;
    private Button bt_num0;
    private Button bt_clear;
    private Button bt_add;
    private Button bt_divide;
    private Button bt_result;
    private Button bt_multiply;
    private Button bt_point;
    private Button bt_reduce;

    private TextView textView;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initViewAndListener();
    }
   //初始化 并且注册监听接口
    private void initViewAndListener(){

        bt_num1 = (Button) findViewById(R.id.bt_num1);
        bt_num1.setOnClickListener(this);

        bt_num2 = (Button) findViewById(R.id.bt_num2);
        bt_num2.setOnClickListener(this);

        bt_num3 = (Button) findViewById(R.id.bt_num3);
        bt_num3.setOnClickListener(this);

        bt_num4 = (Button) findViewById(R.id.bt_num4);
        bt_num4.setOnClickListener(this);

        bt_num5 = (Button) findViewById(R.id.bt_num5);
        bt_num5.setOnClickListener(this);

        bt_num6 = (Button) findViewById(R.id.bt_num6);
        bt_num6.setOnClickListener(this);

        bt_num7 = (Button) findViewById(R.id.bt_num7);
        bt_num7.setOnClickListener(this);

        bt_num8 = (Button) findViewById(R.id.bt_num8);
        bt_num8.setOnClickListener(this);

        bt_num9 = (Button) findViewById(R.id.bt_num9);
        bt_num9.setOnClickListener(this);

        bt_num0 = (Button) findViewById(R.id.bt_num0);
        bt_num0.setOnClickListener(this);

        bt_clear = (Button) findViewById(R.id.bt_clear);
        bt_clear.setOnClickListener(this);

        bt_add = (Button) findViewById(R.id.bt_add);
        bt_add.setOnClickListener(this);

        bt_divide = (Button) findViewById(R.id.bt_divide);
        bt_divide.setOnClickListener(this);

        bt_reduce = (Button) findViewById(R.id.bt_reduce);
        bt_reduce.setOnClickListener(this);

        bt_result = (Button) findViewById(R.id.bt_result);
        bt_result.setOnClickListener(this);

        bt_point = (Button) findViewById(R.id.bt_point);
        bt_point.setOnClickListener(this);

        bt_multiply = (Button) findViewById(R.id.bt_multiply);
        bt_multiply.setOnClickListener(this);

        textView = (TextView) findViewById(R.id.textView);

    }
   private String cText = "";

    @Override
    public void onClick(View v) {



        switch (v.getId()) {
            case R.id.bt_num0:
                textView.setText(textView.getText() + "0");
                cText = cText + "0";
                break;
            case R.id.bt_num1:
                textView.setText(textView.getText() + "1");
                cText = cText + "1";
                break;
            case R.id.bt_num2:
                textView.setText(textView.getText() + "2");
                cText = cText + "2";
                break;
            case R.id.bt_num3:
                textView.setText(textView.getText() + "3");
                cText = cText + "3";
                break;
            case R.id.bt_num4:
                textView.setText(textView.getText() + "4");
                cText = cText + "4";
                break;
            case R.id.bt_num5:
                textView.setText(textView.getText() + "5");
                cText = cText + "5";
                break;
            case R.id.bt_num6:
                textView.setText(textView.getText() + "6");
                cText = cText + "1";
                break;
            case R.id.bt_num7:
                textView.setText(textView.getText() + "7");
                cText = cText + "7";
                break;
            case R.id.bt_num8:
                textView.setText(textView.getText() + "8");
                cText = cText + "8";
                break;
            case R.id.bt_num9:
                textView.setText(textView.getText() + "9");
                cText = cText + "9";
                break;
            case R.id.bt_add:
                textView.setText(textView.getText() + "+");
                cText = cText + "+";
                break;
            case R.id.bt_reduce:
                textView.setText(textView.getText() + "-");
                cText = cText + "-";
                break;
            case R.id.bt_multiply:
                textView.setText(textView.getText() + "*");
                cText = cText + "*";
                break;
            case R.id.bt_divide:
                textView.setText(textView.getText() + "/");
                cText = cText + "/";
                break;
            case R.id.bt_point:
                textView.setText(textView.getText() + ".");
                cText = cText + ".";
                break;
            case R.id.bt_clear:
                textView.setText("");
                cText = "";
                break;
            case R.id.bt_result:
                textView.setText(getResult(cText));
                cText = getResult(cText);
                break;


        }
    }
    //求结果
    public String getResult(String cText){

        if (cText.contains("+")){
           String[] s = cText.split("\\+");//切分字符串 得到只有两个数字字符串的数组
           double one = Double.parseDouble(s[0]);
           double two = Double.parseDouble(s[1]);

            return String.valueOf(one + two);

        }
        else if (cText.contains("-")){
            String[] s = cText.split("\\-");
            double one = Double.parseDouble(s[0]);
            double two = Double.parseDouble(s[1]);
            return String.valueOf(one-two);

        }
        else if (cText.contains("*")){
            String[] s = cText.split("\\*");
            double one = Double.parseDouble(s[0]);
            double two = Double.parseDouble(s[1]);
            return String.valueOf(one*two);

        }
       else if (cText.contains("/")){
            String[] s = cText.split("/");
            double one = Double.parseDouble(s[0]);
            double two = Double.parseDouble(s[1]);
            return String.valueOf(one/two);

        }
        else return "0";

    }
}