簡單四則運算應用A Simple Arithmetic Application on Android System－天天向上

開啟strings.xml準備自定義文字

   1: <?xml version="1.0" encoding="utf-8"?>   2: <resources>   3:     4:     <string name="app_name">ArithmeticTest</string>   5:     <string name="action_settings">Settings</string>   6:     <string name="hello_world">Hello world!</string>   7:     <string name="InputFirstNumber">輸入第一個數字</string>   8:     <string name="InputSecondNumber">輸入第二個數字</string>   9:     <string name="CalResult">計算結果</string>  10:     <string name="Addition">+</string>  11:     <string name="Subtraction">-</string>  12:     <string name="Multiplication">x</string>  13:     <string name="Division">/</string>  14:       15: </resources>

人機介面加入兩個TextEdit和四個按鈕分別對應+-*/符號

以下以+號為例

編輯人機介面完成如下:

執行模擬:

針對按鈕事件開始撰寫主程式MainActivity.java

虛線內為加入的函式庫

   1: package com.example.arithmetictest;   2:     3: import android.os.Bundle;   4: import android.app.Activity;   5: import android.view.Menu;   6: //------------------------------------------------------   7: import android.view.View;   8: import android.view.View.OnClickListener;   9: import android.widget.Button;  10: import android.widget.TextView;  11: import android.widget.EditText;  12: //------------------------------------------------------

加入變數宣告

   1: public class MainActivity extends Activity {   2:     //---------------------------------------------------   3:     private TextView view    = null;    // 資訊顯示    4:     private TextView note    = null;    // 提示    5:     private EditText edtNum1 = null;    // 數字1    6:     private EditText edtNum2 = null;    // 數字2   7:     private Button   btnAdd  = null;    // 加法按鈕   8:     private Button   btnSub  = null;    // 剪髮按鈕    9:     private Button   btnMul  = null;    // 乘法按鈕  10:     private Button   btnDiv  = null;    // 除法按鈕  11:     private int      num1    = 0;       // 儲存第一個數字  12:     private int      num2    = 0;       // 儲存第二個數字   13:     //---------------------------------------------------

onCreate事件加入初始化

   1:     2:         this.edtNum1.setOnClickListener(new OnClickListener(){   3:             @Override   4:             public void onClick(View v){   5:                 MainActivity.this.edtNum1.setText("");    // 清除文字   6:             }   7:            8:         });   9:         this.edtNum2.setOnClickListener(new OnClickListener(){  10:             @Override  11:             public void onClick(View v)  12:             {  13:                 MainActivity.this.edtNum2.setText("");    // 清除文字  14:             }  15:         });  16:         this.btnAdd.setOnClickListener(new OnClickListener(){  17:             @Override  18:             public void onClick(View v){  19:                 MainActivity.this.num1 = Integer.parseInt(MainActivity.this.edtNum1.getText().toString());  20:                 MainActivity.this.num2 = Integer.parseInt(MainActivity.this.edtNum2.getText().toString());  21:                 MainActivity.this.note.setText("+");  22:                 MainActivity.this.view.setText(String.valueOf(num1+num2));  23:             }  24:         });  25:         this.btnSub.setOnClickListener(new OnClickListener(){  26:             @Override  27:             public void onClick(View v)  28:             {  29:                 MainActivity.this.num1 = Integer.parseInt(MainActivity.this.edtNum1.getText().toString());  30:                 MainActivity.this.num2 = Integer.parseInt(MainActivity.this.edtNum2.getText().toString());  31:                 MainActivity.this.note.setText("-");  32:                 MainActivity.this.view.setText(String.valueOf(num1-num2));                  33:             }  34:         });  35:         this.btnMul.setOnClickListener(new OnClickListener(){  36:             @Override  37:             public void onClick(View v){  38:                 MainActivity.this.num1 = Integer.parseInt(MainActivity.this.edtNum1.getText().toString());  39:                 MainActivity.this.num2 = Integer.parseInt(MainActivity.this.edtNum2.getText().toString());  40:                 MainActivity.this.note.setText("*");  41:                 MainActivity.this.view.setText(String.valueOf(num1*num2));  42:             }  43:         });  44:         this.btnDiv.setOnClickListener(new OnClickListener(){  45:             @Override  46:             public void onClick(View v)  47:             {  48:                 MainActivity.this.num1 = Integer.parseInt(MainActivity.this.edtNum1.getText().toString());  49:                 MainActivity.this.num2 = Integer.parseInt(MainActivity.this.edtNum2.getText().toString());  50:                 MainActivity.this.note.setText("/");  51:                 MainActivity.this.view.setText(String.valueOf(num1/num2));                  52:             }  53:         });  54:         //---------------------------------------------------    