- 修改符号使其符合用户直觉，如“ = ”、“ CLC”
- 更改配色
- 更改排版布局，使其放松不拥挤
常规计算器点按加减乘除会互相切换，但这份代码没有实现这个功能，当按下某一个算法符号后，不能切换其他的算法符号。
例如我想要计算“1 + 1”的结果，但是误触到“ - ”后，不能直接点按“ + ”更改算法符号，需要全部清除后重新输入。
通过在加减乘除的监听事件中修改如下代码实现直接切换的功能，以加法为例：
case R.id.jian: {
if (ss.length() == 0) {
edit.setText("0 - ");
ss = "0 - ";
break;
}
if (ss.contains("+")||ss.contains("-")||ss.contains("x")||ss.contains("/")) {
ss = ss.substring(0,ss.length()-3);
ss += " - ";
edit.setText(ss);
break;
}具体演示见视频。
below is "MainActivity.java"
package com.example.myapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
Button btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9, btn0; // 数字按钮
Button jia, jian, cheng, chu, dian, sum, clear,back;// +号
EditText edit; // 显示文本
private String ss = "";//设置一个String类型的变量
private String ss1 = "1 + ";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 获取页面上的控件
btn1 = findViewById(R.id.btn1);
btn2 = findViewById(R.id.btn2);
btn3 = findViewById(R.id.btn3);
btn4 = findViewById(R.id.btn4);
btn5 = findViewById(R.id.btn5);
btn6 = findViewById(R.id.btn6);
btn7 = findViewById(R.id.btn7);
btn8 = findViewById(R.id.btn8);
btn9 = findViewById(R.id.btn9);
btn0 = findViewById(R.id.btn0);
jia = findViewById(R.id.jia);
jian = findViewById(R.id.jian);
cheng = findViewById(R.id.cheng);
chu = findViewById(R.id.chu);
sum = findViewById(R.id.calculation);
dian = findViewById(R.id.dian);
clear = findViewById(R.id.clear);
edit = findViewById(R.id.edit);
back = findViewById(R.id.back);
// 按钮的单击事件
btn1.setOnClickListener(new Click());
btn2.setOnClickListener(new Click());
btn3.setOnClickListener(new Click());
btn4.setOnClickListener(new Click());
btn5.setOnClickListener(new Click());
btn6.setOnClickListener(new Click());
btn7.setOnClickListener(new Click());
btn8.setOnClickListener(new Click());
btn9.setOnClickListener(new Click());
btn0.setOnClickListener(new Click());
jia.setOnClickListener(new Click());
jian.setOnClickListener(new Click());
cheng.setOnClickListener(new Click());
chu.setOnClickListener(new Click());
sum.setOnClickListener(new Click());
dian.setOnClickListener(new Click());
clear.setOnClickListener(new Click());
edit.setOnClickListener(new Click());
back.setOnClickListener(new Click());
}
// 设置按钮点击后的监听
class Click implements View.OnClickListener {
public void onClick(View v) {
switch (v.getId()) { //switch循环获取点击按钮后的值
case R.id.clear: {
ss = "";
edit.setText(ss);//在edittext里面显示字符串ss
}
break;
case R.id.btn0: {
ss += "0";
edit.setText(ss);
}
break;
case R.id.btn1: {
ss += "1"; // ss=ss+1
edit.setText(ss);
}
break;
case R.id.btn2: {
ss += "2";
edit.setText(ss);
}
break;
case R.id.btn3: {
ss += "3";
edit.setText(ss);
}
break;
case R.id.btn4: {
ss += "4";
edit.setText(ss);
}
break;
case R.id.btn5: {
ss += "5";
edit.setText(ss);
}
break;
case R.id.btn6: {
ss += "6";
edit.setText(ss);
}
break;
case R.id.btn7: {
ss += "7";
edit.setText(ss);
}
break;
case R.id.btn8: {
ss += "8";
edit.setText(ss);
}
break;
case R.id.btn9: {
ss += "9";
edit.setText(ss);
}
break;
case R.id.dian: {
if (ss.length() == 0) {
break;
} else {
ss += ".";
edit.setText(ss);
}
}
break;
case R.id.jia: {
if (ss.length() == 0) {
edit.setText("0 + ");
ss = "0 + ";
break;
}
if (ss.contains("+")||ss.contains("-")||ss.contains("x")||ss.contains("/")) {
ss = ss.substring(0,ss.length()-3);
ss += " + ";
edit.setText(ss);
break;
}
ss += " + ";
edit.setText(ss);
}
break;
case R.id.jian: {
if (ss.length() == 0) {
edit.setText("0 - ");
ss = "0 - ";
break;
}
if (ss.contains("+")||ss.contains("-")||ss.contains("x")||ss.contains("/")) {
ss = ss.substring(0,ss.length()-3);
ss += " - ";
edit.setText(ss);
break;
}
ss += " - ";
edit.setText(ss);
}
break;
case R.id.cheng: {
if (ss.length() == 0) {
edit.setText("0 × ");
ss = "0 × ";
break;
}
if (ss.contains("+")||ss.contains("-")||ss.contains("x")||ss.contains("/")) {
ss = ss.substring(0,ss.length()-3);
ss += " x ";
edit.setText(ss);
break;
}
ss += " × ";
edit.setText(ss);
}
break;
case R.id.chu: {
if (ss.length() == 0) {
edit.setText("0 / ");
ss = "0 / ";
break;
}
if (ss.contains("+")||ss.contains("-")||ss.contains("x")||ss.contains("/")) {
ss = ss.substring(0,ss.length()-3);
ss += " / ";
edit.setText(ss);
break;
}
ss += " / ";
edit.setText(ss);
}
break;
case R.id.calculation:
getResult();
break;
case R.id.back: {
if (ss.contains(" ")){
if (ss.indexOf(" ") == ss.length() - 3) {
ss = ss.substring(0, ss.length() - 3);
edit.setText(ss);
break;
}
}
ss = ss.substring(0, ss.length() - 1);
edit.setText(ss);
break;
}
}
}
}
private void getResult() {
double result = 0;
if (ss == null || ss.equals("")) return;
if (!ss.contains(" ")) return;
String s1 = ss.substring(0, ss.indexOf(" "));
String op = ss.substring(ss.indexOf(" ") + 1, ss.indexOf(" ") + 2);
String s2 = ss.substring(ss.indexOf(" ") + 3);
if (!s1.equals("") && !s2.equals("")) {
// float d1 = Float.parseFloat(s1);
// float d2 = Float.parseFloat(s2);
double d1 = Double.parseDouble(s1);
double d2 = Double.parseDouble(s2);
switch (op) {
case "+":
result = d1 + d2;
break;
case "-":
result = d1 - d2;
break;
case "×":
result = d1 * d2;
break;
case "/": {
if (d2 == 0) {
Toast.makeText(MainActivity.this, "不能除以零", Toast.LENGTH_SHORT).show();
break;
}
result = d1 / d2 * 1.0;
}
break;
}
// edit.setText(result + "");
// ss = "" + result;
int r = (int) result;
if (r == result) {
edit.setText("" + r);
ss = "" + r;
} else {
ss = "" + result; //将double类型的result转成string类型的数据存储在ss中
ss = ss.substring(0,ss.length()-1);
// edit.setText(result+ "");
edit.setText(ss);
}
}
}
}below is "activity_main.xml"
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="30dp"
android:background="#efefef">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="计算器"
android:textSize="40sp"
android:textColor="#999999"
android:layout_marginBottom="30dp"
android:gravity="center"/>
<EditText
android:id="@+id/edit"
android:textSize="40dp"
android:layout_width="match_parent"
android:layout_height="100dp"
android:gravity="end|bottom"
/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/clear"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:layout_weight="1"
android:text="clc"
android:textSize="25dp"/>
<Button
android:id="@+id/calculation"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:layout_weight="1"
android:text="="
android:textSize="25dp" />
</LinearLayout>
<GridLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:rowCount="4"
android:columnCount="4"
>
<Button
android:id="@+id/btn1"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="1"
android:textSize="25sp"/>
<Button
android:id="@+id/btn2"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="2"
android:textSize="25sp"/>
<Button
android:id="@+id/btn3"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="3"
android:textSize="25sp"/>
<Button
android:id="@+id/jia"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_row="0"
android:layout_margin="6dp"
android:text="+"
android:textSize="25sp" />
<Button
android:id="@+id/btn4"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="4"
android:textSize="25sp"/>
<Button
android:id="@+id/btn5"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="5"
android:textSize="25sp"/>
<Button
android:id="@+id/btn6"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="6"
android:textSize="25sp"/>
<Button
android:id="@+id/jian"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="-"
android:textSize="25sp"/>
<Button
android:id="@+id/btn7"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="7"
android:textSize="25sp"/>
<Button
android:id="@+id/btn8"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="8"
android:textSize="25sp"/>
<Button
android:id="@+id/btn9"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="9"
android:textSize="25sp"/>
<Button
android:id="@+id/cheng"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="x"
android:textAllCaps="false"
android:textSize="25sp"/>
<Button
android:id="@+id/btn0"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="0"
android:textSize="25sp"/>
<Button
android:id="@+id/dian"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="."
android:textSize="25sp"/>
<Button
android:id="@+id/back"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="⬅"
android:textSize="25sp"/>
<Button
android:id="@+id/chu"
android:layout_width="70dp"
android:layout_height="wrap_content"
android:layout_margin="6dp"
android:text="÷"
android:textSize="25sp"/>
</GridLayout>
</LinearLayout>below is "theme.xml"
<resources xmlns:tools="http://schemas.android.com/tools">
<!-- Base application theme. -->
<style name="Theme.MyApplication" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
<!-- Primary brand color. -->
<item name="colorPrimary">@color/grey</item>
<item name="colorPrimaryVariant">@color/darkGrey</item>
<item name="colorOnPrimary">@color/white</item>
<!-- Secondary brand color. -->
<item name="colorSecondary">@color/teal_200</item>
<item name="colorSecondaryVariant">@color/teal_700</item>
<item name="colorOnSecondary">@color/black</item>
<!-- Status bar color. -->
<item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
<!-- Customize your theme here. -->
</style>
</resources>below is "color.xml"
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="purple_200">#FFBB86FC</color>
<color name="purple_500">#FF6200EE</color>
<color name="purple_700">#FF3700B3</color>
<color name="teal_200">#9cc679</color>
<color name="teal_700">#79a852</color>
<color name="black">#FF000000</color>
<color name="white">#FFFFFFFF</color>
<color name="grey">#a3a3a3</color>
<color name="darkGrey">#5e5e5e</color>
</resources>