Android studio design simple calculator

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The first step, simple interface layout

<?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=".MainActivity"
    android:background="#000000">

    <TextView
        android:id="@+id/text1"
        android:layout_width="match_parent"
        android:layout_height="170dp"
        android:layout_marginLeft="10dp"
        android:layout_marginTop="10dp"
        android:layout_marginRight="10dp"
        android:background="#ffffff"
        android:gravity="right|bottom"
        android:hint="0"
        android:paddingRight="5dp"
        android:textColor="#000000"
        android:textSize="40sp" />
    <LinearLayout
        android:id="@+id/relative"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginLeft="10dp"
        android:orientation="vertical">

        <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
        <Button
            android:id="@+id/btn_7"
            style="@style/ButtonStyle"
            android:text="@string/btn_7" />
        <Button
            android:id="@+id/btn_8"
            style="@style/ButtonStyle"
            android:text="@string/btn_8" />
        <Button
            android:id="@+id/btn_9"
            style="@style/ButtonStyle"
            android:text="@string/btn_9" />
        <Button
            android:id="@+id/btn_clear"
            style="@style/ButtonStyle"
            android:text="@string/btn_clear"/>
    </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            <Button
                android:id="@+id/btn_4"
                style="@style/ButtonStyle"
                android:text="@string/btn_4" />
            <Button
                android:id="@+id/btn_5"
                style="@style/ButtonStyle"
                android:text="@string/btn_5" />
            <Button
                android:id="@+id/btn_6"
                style="@style/ButtonStyle"
                android:text="@string/btn_6" />
            <Button
                android:id="@+id/btn_plus"
                style="@style/ButtonStyle"
                android:text="@string/btn_plus"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            <Button
                android:id="@+id/btn_1"
                style="@style/ButtonStyle"
                android:text="@string/btn_1" />
            <Button
                android:id="@+id/btn_2"
                style="@style/ButtonStyle"
                android:text="@string/btn_2" />
            <Button
                android:id="@+id/btn_3"
                style="@style/ButtonStyle"
                android:text="@string/btn_3" />
            <Button
                android:id="@+id/btn_minus"
                style="@style/ButtonStyle"
                android:text="@string/btn_minus"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            <Button
                android:id="@+id/btn_0"
                style="@style/ButtonStyle"
                android:text="@string/btn_0" />
            <Button
                android:id="@+id/btn_equal"
                style="@style/ButtonEqualStyle"
                android:text="@string/btn_equal" />
            <Button
                android:id="@+id/btn_divide"
                style="@style/ButtonStyle"
                android:text="@string/btn_divide" />
            <Button
                android:id="@+id/btn_multiply"
                style="@style/ButtonStyle"
                android:text="@string/btn_multiply"/>
        </LinearLayout>
    </LinearLayout>

</LinearLayout>

 

string.xml file

<resources>
    <string name="app_name">计算器</string>
    <string name="text1">显示文本框</string>
    <string name="relative">布局</string>
    <string name="btn_1">1</string>
    <string name="btn_2">2</string>
    <string name="btn_3">3</string>
    <string name="btn_4">4</string>
    <string name="btn_5">5</string>
    <string name="btn_6">6</string>
    <string name="btn_7">7</string>
    <string name="btn_8">8</string>
    <string name="btn_9">9</string>
    <string name="btn_0">0</string>
    <string name="btn_clear">C</string>
    <string name="btn_plus">+</string>
    <string name="btn_minus">-</string>
    <string name="btn_multiply">×</string>
    <string name="btn_divide">÷</string>
    <string name="btn_equal">=</string>
</resources>

LinearLayout linear layout is used, but since the basic properties of the button, so that by way of using the style set, as follows

<resources>
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>
    <style name="ButtonBaseStyle">
        <item name="android:layout_width">40dp</item>
        <item name="android:layout_height">70dp</item>
        <item name="android:layout_margin">10dp</item>
        <item name="android:padding">10dp</item>
        <item name="android:textColor">@android:color/black</item>
        <item name="android:textSize">30sp</item>
    </style>
    <style name="ButtonStyle" parent="ButtonBaseStyle">
        <item name="android:background">@drawable/bg_selector</item>
        <item name="android:layout_weight">1</item>
    </style>
    <style name="ButtonEqualStyle" parent="ButtonBaseStyle">
        <item name="android:background">@drawable/ping_bg</item>
        <item name="android:layout_weight">1</item>
    </style>
</resources>

white_bg.xml file

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<corners android:radius="5dp"/>
    <solid android:color="#ffffff"/>
</shape>

pink_bg.xml file

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<corners android:radius="5dp"></corners>
    <solid android:color="#ee82ee"></solid>
</shape>

selector_bg.xml file

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/white_bg" android:state_pressed="false"></item>
    <item android:drawable="@drawable/ping_bg"
        android:state_pressed="true"></item>
</selector>

Event Java code

For quick and easy to set each button to listen to events, the buttons are placed inside an array, and then use the button to add the for statement to listen for events.

In the onClick () put in, you will first get id of the text box (note the text box id).

Then get the text inside the input box. After obtaining the string, to use a switch or a statement for the determination button click, click on only when the number buttons 0 to 9, the input will not break off the front of all the characters will be connected to form a character string is displayed in the text box.

Note: If you click the first number is 0, then only displays the digital input back to zero.

 

 

package com.example.exp3;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        int[] ids = {R.id.btn_0, R.id.btn_1, R.id.btn_2, R.id.btn_3, R.id.btn_4, R.id.btn_4,
                R.id.btn_5, R.id.btn_6, R.id.btn_7, R.id.btn_8, R.id.btn_9, R.id.btn_equal,
                R.id.btn_clear, R.id.btn_multiply, R.id.btn_minus, R.id.btn_divide, R.id.btn_plus};
        //将所有按钮整合成一个数组
        for (int i = 0; i < ids.length; i++)
            findViewById(ids[i]).setOnClickListener(this);//给每个按钮设置一个监听事件
    }
    @Override
    public void onClick(View v) {
        TextView tv_input = (TextView) findViewById(R.id.text1);
        Button btn = (Button)v;
        String str=tv_input.getText().toString();//获取xml那里的输入
        String strButton =btn.getText().toString();//点击按钮得到的文本
        switch (v.getId()){
            case R.id.btn_0:
            case R.id.btn_1:
            case R.id.btn_2:
            case R.id.btn_3:
            case R.id.btn_4:
            case R.id.btn_5:
            case R.id.btn_6:
            case R.id.btn_7:
            case R.id.btn_8:
            case R.id.btn_9:
                if (str.equals("0"))
                    tv_input.setText(strButton);
                else
                    tv_input.setText(str+strButton);
                break;
            case R.id.btn_clear:
                tv_input.setText("0");
                break;
            case R.id.btn_plus:
            case R.id.btn_minus:
            case R.id.btn_multiply:
            case R.id.btn_divide:
                tv_input.setText(str+strButton);
                break;
            case R.id.btn_equal:
                MyCalc obj=new MyCalc(str);
                double ret = obj.Calc();
                int Ret = (int)ret;
                if (ret == Ret)
                    tv_input.setText(String.valueOf(Ret));
                else
                    tv_input.setText(String.valueOf(ret));
                break;
        }
    }

    class MyCalc {
        private String input;

        public MyCalc(String input) {
            this.input = input;
        }

        public double Calc() {
            if (TextUtils.isEmpty(input))
                return 0;
            Pattern pattern = Pattern.compile("[+(×)(÷)/-]");
            String[] nums = pattern.split(input);
            Matcher matcher = pattern.matcher(input);
            if (matcher.find() == false)
                return 0;
            String op = matcher.group(0);
            double first = Double.parseDouble(nums[0]);
            double second = Double.parseDouble(nums[1]);
            double sum = 0;
            try {
                switch (op) {
                    case "+":
                        sum = first + second;
                        break;
                    case "-":
                        sum = first - second;
                        break;
                    case "×":
                        sum = first * second;
                        break;
                    case "÷":
                        sum = first / second;
                        break;
                }
            } catch (Exception e) {
                Toast.makeText(MainActivity.this, "出错", Toast.LENGTH_LONG).show();
            }
            return sum;
        }
    }
}