首页分享移动应用开发之安卓计算器的实现

移动应用开发之安卓计算器的实现

来源：花匠小妙招时间：2024-11-14 13:10

参考博文：安卓简易计算器

自己重新编写了布局，MainActivity也做了一些小的更改，代码更舒服了一些，逻辑没有什么改动。

效果图和功能说明

功能：
1.只能进行简单的两操作数的加减乘除
2.清空
3.回退一个输入的字符

效果：
在这里插入图片描述

代码 1.布局文件activity_main.xml

<?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout 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" tools:context=".MainActivity" tools:layout_editor_absoluteY="81dp"> <TextView android:id="@+id/textView1" android:layout_width="354dp" android:layout_height="64dp" android:layout_alignLeft="@+id/editText1" android:layout_alignRight="@+id/editText1" android:layout_alignParentTop="true" android:layout_marginStart="14dp" android:layout_marginLeft="14dp" android:layout_marginTop="57dp" android:layout_marginBottom="158dp" android:textAppearance="?android:attr/textAppearanceLarge" android:textColor="#000" android:textSize="28dp" app:layout_constraintBottom_toTopOf="@+id/buttonPanel" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <EditText android:id="@+id/editText1" android:layout_width="411dp" android:layout_height="0dp" android:layout_below="@+id/textView1" android:layout_marginTop="16dp" android:layout_marginBottom="17dp" android:ems="10" android:singleLine="true" android:textColor="#000" android:textSize="35dp" app:layout_constraintBottom_toTopOf="@+id/buttonPanel" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <TableLayout android:id="@+id/buttonPanel" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="9dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/textView1"> <TableRow android:layout_width="match_parent" android:layout_height="match_parent"> <Button android:id="@+id/buttonH" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btH" android:textSize="23dp" tools:layout_editor_absoluteX="16dp" tools:layout_editor_absoluteY="274dp" /> <Button android:id="@+id/buttonClear" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btClear" android:textSize="23dp" tools:layout_editor_absoluteX="16dp" tools:layout_editor_absoluteY="274dp" /> <Button android:id="@+id/buttonBack" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btBack" android:textSize="23dp" tools:layout_editor_absoluteX="105dp" tools:layout_editor_absoluteY="274dp" /> <Button android:id="@+id/buttonOp3" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btOp3" android:textSize="23dp" tools:layout_editor_absoluteX="305dp" tools:layout_editor_absoluteY="402dp" /> </TableRow> <TableRow android:layout_width="match_parent" android:layout_height="match_parent"> <Button android:id="@+id/buttonNum1" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btNum1" android:textSize="23dp" tools:layout_editor_absoluteX="16dp" tools:layout_editor_absoluteY="338dp" /> <Button android:id="@+id/buttonNum2" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btNum2" android:textSize="23dp" tools:layout_editor_absoluteX="105dp" tools:layout_editor_absoluteY="338dp" /> <Button android:id="@+id/buttonNum3" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btNum3" android:textSize="23dp" tools:layout_editor_absoluteX="195dp" tools:layout_editor_absoluteY="338dp" /> <Button android:id="@+id/buttonOp1" android:layout_width="105dp" android:layout_height="65dp" android:text="+" tools:layout_editor_absoluteX="305dp" tools:layout_editor_absoluteY="338dp" /> </TableRow> <TableRow android:layout_width="match_parent" android:layout_height="match_parent"> <Button android:id="@+id/buttonNum4" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btNum4" android:textSize="23dp" tools:layout_editor_absoluteX="16dp" tools:layout_editor_absoluteY="402dp" /> <Button android:id="@+id/buttonNum5" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btNum5" android:textSize="23dp" tools:layout_editor_absoluteX="106dp" tools:layout_editor_absoluteY="402dp" /> <Button android:id="@+id/buttonNum6" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btNum6" android:textSize="23dp" tools:layout_editor_absoluteX="196dp" tools:layout_editor_absoluteY="402dp" /> <Button android:id="@+id/buttonOp2" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btOp2" android:textSize="23dp" tools:layout_editor_absoluteX="305dp" tools:layout_editor_absoluteY="337dp" /> </TableRow> <TableRow android:layout_width="match_parent" android:layout_height="match_parent"> <Button android:id="@+id/buttonNum7" android:layout_width="105dp" android:layout_height="64dp" android:text="@string/btNum7" android:textSize="23dp" tools:layout_editor_absoluteX="16dp" tools:layout_editor_absoluteY="467dp" /> <Button android:id="@+id/buttonNum8" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btNum8" android:textSize="23dp" tools:layout_editor_absoluteX="105dp" tools:layout_editor_absoluteY="468dp" /> <Button android:id="@+id/buttonNum9" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btNum9" android:textSize="23dp" tools:layout_editor_absoluteX="195dp" tools:layout_editor_absoluteY="467dp" /> <Button android:id="@+id/buttonOp4" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btOp4" android:textSize="23dp" tools:layout_editor_absoluteX="305dp" tools:layout_editor_absoluteY="468dp" /> </TableRow> <TableRow android:layout_width="match_parent" android:layout_height="match_parent"> <Button android:id="@+id/buttonPoint" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btPoint" android:textSize="23dp" tools:layout_editor_absoluteX="195dp" tools:layout_editor_absoluteY="534dp" /> <Button android:id="@+id/buttonNum0" android:layout_width="105dp" android:layout_height="65dp" android:text="@string/btNum0" android:textSize="23dp" tools:layout_editor_absoluteX="10dp" tools:layout_editor_absoluteY="534dp" /> <Button android:id="@+id/buttonEqual" android:layout_width="105dp" android:layout_height="65dp" android:layout_weight="2" android:text="@string/btEq" android:textSize="23dp" tools:layout_editor_absoluteX="306dp" tools:layout_editor_absoluteY="534dp" /> </TableRow> </TableLayout> </android.support.constraint.ConstraintLayout>

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255 2.strings.xml

<resources> <string name="app_name">MyCalculator</string> <string name="btNum1">1</string> <string name="btNum2">2</string> <string name="btNum3">3</string> <string name="btNum4">4</string> <string name="btNum5">5</string> <string name="btNum6">6</string> <string name="btNum7">7</string> <string name="btNum8">8</string> <string name="btNum9">9</string> <string name="btNum0">0</string> <string name="btPoint">.</string> <string name="btOp1">+</string> <string name="btOp2">-</string> <string name="btOp3">*</string> <string name="btOp4">÷</string> <string name="btBack">back</string> <string name="btClear">C</string> <string name="btH">%</string> <string name="btEq">=</string> <string name="btTextSize">23dp</string> <string name="btWidth">105dp</string> <string name="btHeight">65dp</string> </resources>

12345678910111213141516171819202122232425262728 3.MainActivity.java

我们来理一下如何获取editText以及TextView中的内容：
1.声明对应类型的私有变量
2.将变量通过findViewById(R.id.xxx)进行实例化
3.获取控件上的字符串（以editText为例）：editText.getText().toString();
4.设置控件上的文字（以editText为例）：editText.setText()

package com.example.yogi.mycalculator; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; public class MainActivity extends Activity implements OnClickListener{ private Button btn[] = new Button[18]; private EditText editText;//显示输入的数字 private TextView textView; private String opt = "+";//操作符 private double n1 = 0.0, n2 = 0.0;//两个操作数 @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //实例化获取按钮的id btn[0] = (Button) findViewById(R.id.buttonNum0); btn[1] = (Button) findViewById(R.id.buttonNum1); btn[2] = (Button) findViewById(R.id.buttonNum2); btn[3] = (Button) findViewById(R.id.buttonNum3); btn[4] = (Button) findViewById(R.id.buttonNum4); btn[5] = (Button) findViewById(R.id.buttonNum5); btn[6] = (Button) findViewById(R.id.buttonNum6); btn[7] = (Button) findViewById(R.id.buttonNum7); btn[8] = (Button) findViewById(R.id.buttonNum8); btn[9] = (Button) findViewById(R.id.buttonNum9); btn[10] = (Button) findViewById(R.id.buttonOp1); btn[11] = (Button) findViewById(R.id.buttonOp2); btn[12] = (Button) findViewById(R.id.buttonOp3); btn[13] = (Button) findViewById(R.id.buttonOp4); btn[14] = (Button) findViewById(R.id.buttonEqual); btn[15] = (Button) findViewById(R.id.buttonPoint); btn[16] = (Button) findViewById(R.id.buttonClear); btn[17] = (Button) findViewById(R.id.buttonBack); editText = (EditText)findViewById(R.id.editText1); textView = (TextView)findViewById(R.id.textView1); //为按钮添加监听器 for(int i=0;i<18;i++){ btn[i].setOnClickListener(this); } } @Override public void onClick(View v) { // TODO Auto-generated method stub String s = editText.getText().toString();//获取字符串 try{ switch(v.getId()) { case R.id.buttonNum1: case R.id.buttonNum2: case R.id.buttonNum3: case R.id.buttonNum4: case R.id.buttonNum5: case R.id.buttonNum6: case R.id.buttonNum7: case R.id.buttonNum8: case R.id.buttonNum9: case R.id.buttonNum0: { String str = editText.getText().toString(); editText.setText(str + ((Button) v).getText()); break; } case R.id.buttonEqual://操作符= { if(opt == "+") { String str = editText.getText().toString(); n2 = Double.parseDouble(str); textView.setText(n1 + opt + n2 + "="); editText.setText((n1 + n2) + ""); } else if(opt == "-") { String str = editText.getText().toString(); n2 = Double.parseDouble(str); textView.setText(n1 + opt + n2 + "="); editText.setText((n1 - n2) + ""); } else if(opt == "*") { String str = editText.getText().toString(); n2 = Double.parseDouble(str); textView.setText(n1 + opt + n2 + "="); editText.setText((n1 * n2) + ""); } else if(opt == "/") { String str = editText.getText().toString(); n2 = Double.parseDouble(str); if(n2 == 0) { editText.setText(""); textView.setText("除数不能为0"); break; } else { textView.setText(n1 + opt + n2 + "="); editText.setText((n1 / n2) + ""); } } break; } case R.id.buttonPoint://. { String str = editText.getText().toString(); if(str.indexOf(".") != -1) //判断字符串中是否已经包含了小数点，如果有就什么也不做 { } else //如果没有小数点 { if(str.equals("0"))//如果开始为0， editText.setText(("0" + ".").toString()); else if(str.equals(""))//如果初时显示为空，就什么也不做 { } else editText.setText(str + "."); } break; } case R.id.buttonOp4://操作符 / { String str = editText.getText().toString(); n1 = Double.parseDouble(str); opt = "/"; editText.setText(""); textView.setText(n1 + opt); break; } case R.id.buttonOp3://操作符* { String str = editText.getText().toString(); n1 = Double.parseDouble(str); opt = "*"; editText.setText(""); textView.setText(n1 + opt); break; } case R.id.buttonOp2://操作符- { String str = editText.getText().toString(); n1 = Double.parseDouble(str); opt = "-"; editText.setText(""); textView.setText(n1 + opt); break; } case R.id.buttonOp1://+ { String str = editText.getText().toString(); n1 = Double.parseDouble(str); opt = "+"; textView.setText(n1 + opt); editText.setText(""); break; } case R.id.buttonClear://C { String str =editText.getText().toString(); if(str.length() > 0) editText.setText(""); textView.setText(""); break; } case R.id.buttonBack://back { String str =editText.getText().toString(); if(str.length() > 0) editText.setText(str.substring(0, str.length() - 1)); break; } } }catch(Exception e){} } }