2012年4月6日 星期五

【Android】計算機





上學期上課寫的計算機，寫好用Stack的寫法之後，想說再試試看用樹狀結構跑中序，有bug，又想說哪一天有空再來改，結果一拖就是一學期...

layout
  1. <?xml version="1.0" encoding="utf-8"?>
  2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  3.     android:orientation="vertical" android:layout_width="match_parent"
  4.     android:layout_height="match_parent">
  5.     <EditText android:layout_height="wrap_content" android:id="@+id/editText_result"
  6.         android:layout_width="match_parent" android:hint="1+2-3" android:focusable="false">
  7.     </EditText>
  8.  
  9.     <TableLayout android:layout_width="match_parent"
  10.         android:layout_height="wrap_content" android:stretchColumns="*">
  11.         <TableRow>
  12.             <Button android:text="1" android:id="@+id/button_num1"
  13.                 android:layout_width="match_parent" android:layout_height="wrap_content" />
  14.             <Button android:text="2" android:id="@+id/button_num2"
  15.                 android:layout_width="match_parent" android:layout_height="wrap_content" />
  16.             <Button android:text="3" android:id="@+id/button_num3"
  17.                 android:layout_height="wrap_content" android:layout_width="match_parent" />
  18.         </TableRow>
  19.         <TableRow>
  20.             <Button android:text="4" android:id="@+id/button_num4"
  21.                 android:layout_width="match_parent" android:layout_height="wrap_content" />
  22.             <Button android:text="5" android:id="@+id/button_num5"
  23.                 android:layout_width="match_parent" android:layout_height="wrap_content" />
  24.             <Button android:text="6" android:id="@+id/button_num6"
  25.                 android:layout_height="wrap_content" android:layout_width="match_parent" />
  26.         </TableRow>
  27.         <TableRow>
  28.             <Button android:text="7" android:id="@+id/button_num7"
  29.                 android:layout_width="match_parent" android:layout_height="wrap_content" />
  30.             <Button android:text="8" android:id="@+id/button_num8"
  31.                 android:layout_width="match_parent" android:layout_height="wrap_content" />
  32.             <Button android:text="9" android:id="@+id/button_num9"
  33.                 android:layout_height="wrap_content" android:layout_width="match_parent" />
  34.         </TableRow>
  35.         <TableRow>
  36.             <Button android:text="+" android:id="@+id/button_plus"
  37.                 android:layout_width="match_parent" android:layout_height="wrap_content" />
  38.             <Button android:text="-" android:id="@+id/button_sub"
  39.                 android:layout_width="match_parent" android:layout_height="wrap_content" />
  40.             <Button android:text="=" android:id="@+id/button_amount"
  41.                 android:layout_height="wrap_content" android:layout_width="match_parent" />
  42.         </TableRow>
  43.     </TableLayout>
  44.  
  45. </LinearLayout>

第一種 使用Stack
原理就是把符號跟數字分別拆到個別的Stack，然後再put出來，依據符號進行計算。
  1. package npust.edu.klab;
  2.  
  3. import java.util.Stack;
  4.  
  5. import android.app.Activity;
  6. import android.os.Bundle;
  7. import android.view.View;
  8. import android.view.View.OnClickListener;
  9. import android.view.inputmethod.InputMethodManager;
  10. import android.widget.Button;
  11. import android.widget.EditText;
  12.  
  13. public class Calculator extends Activity {
  14.  
  15.     @Override
  16.     public void onCreate(Bundle savedInstanceState) {
  17.         super.onCreate(savedInstanceState);
  18.         setContentView(R.layout.main);
  19.         
  20.         // set all ui component.
  21.         final EditText edtxt_result = (EditText) this
  22.                 .findViewById(R.id.editText_result);
  23.         Button btn_amount = (Button) this.findViewById(R.id.button_amount);
  24.         
  25.         //to hide the virtual keyboard.
  26.         InputMethodManager imm = (InputMethodManager)getSystemService(INPUT_METHOD_SERVICE);                
  27.         imm.hideSoftInputFromWindow(edtxt_result.getWindowToken(), 0);
  28.         
  29.         // get all button then set a listener for general.
  30.         Button[] btns = { (Button) this.findViewById(R.id.button_num1),
  31.                 (Button) this.findViewById(R.id.button_num2),
  32.                 (Button) this.findViewById(R.id.button_num3),
  33.                 (Button) this.findViewById(R.id.button_num4),
  34.                 (Button) this.findViewById(R.id.button_num5),
  35.                 (Button) this.findViewById(R.id.button_num6),
  36.                 (Button) this.findViewById(R.id.button_num7),
  37.                 (Button) this.findViewById(R.id.button_num8),
  38.                 (Button) this.findViewById(R.id.button_num9),
  39.                 (Button) this.findViewById(R.id.button_plus),
  40.                 (Button) this.findViewById(R.id.button_sub) };
  41.  
  42.         OnClickListener generalOnClick = new OnClickListener() {
  43.             public void onClick(View v) {
  44.                 // set the txt of editText plus the text of button.
  45.                 edtxt_result.setText(edtxt_result.getText().toString()
  46.                         + ((Button) v).getText());
  47.             }
  48.         };
  49.  
  50.         for (Button btn : btns)
  51.             btn.setOnClickListener(generalOnClick);
  52.  
  53.         // calculate
  54.         btn_amount.setOnClickListener(new OnClickListener() {
  55.             public void onClick(View v) {
  56.  
  57.                 String formula = edtxt_result.getText().toString();
  58.                 // stacks for '+'、'-' and numbers.
  59.                 Stack symbols = new Stack();
  60.                 Stack nums = new Stack();
  61.                 // split by '+'、'-'
  62.                 String[] numAry = formula.toString().split("[\\+\\-/]");
  64.                 // set stacks.
  65.                 for (String num : numAry)
  66.                     nums.push(Integer.valueOf(num));
  67.                 for (char c : formula.toCharArray())
  68.                     if (c == '+' || c == '-')
  69.                         symbols.push(c);
  71.                 // calculate by symbol.
  72.                 int result = 0;
  73.                 while (!symbols.isEmpty()) {
  74.                     switch (symbols.pop()) {
  75.                     case '+':
  76.                         result += nums.pop();
  77.                         break;
  78.                     case '-':
  79.                         result -= nums.pop();
  80.                         break;
  81.                     }
  82.                 }
  84.                 // plus the last num in stack.
  85.                 result += nums.pop();
  86.                 if(result<0){
  87.                     edtxt_result.setText("");
  88.                     edtxt_result.setHint("不支援負數計算");
  89.                 }
  90.                 else
  91.                     edtxt_result.setText(result + "");
  92.             }
  93.         });
  94.     }
  95. }

第二種 使用樹狀結構
就是依據樹狀中序去做運算，結構如圖。

  1. package npust.edu.klab;
  2.  
  3.  
  4. import android.app.Activity;
  5. import android.os.Bundle;
  6. import android.view.View;
  7. import android.view.View.OnClickListener;
  8. import android.view.inputmethod.InputMethodManager;
  9. import android.widget.Button;
  10. import android.widget.EditText;
  11.  
  12. public class Calculator extends Activity {
  13.  
  14.     @Override
  15.     public void onCreate(Bundle savedInstanceState) {
  16.         super.onCreate(savedInstanceState);
  17.         setContentView(R.layout.main);
  18.  
  19.         // set all ui component.
  20.         final EditText edtxt_result = (EditText) this
  21.                 .findViewById(R.id.editText_result);
  22.         Button btn_amount = (Button) this.findViewById(R.id.button_amount);
  23.  
  24.         // to hide the virtual keyboard.
  25.         InputMethodManager imm = (InputMethodManager) getSystemService(INPUT_METHOD_SERVICE);
  26.         imm.hideSoftInputFromWindow(edtxt_result.getWindowToken(), 0);
  27.  
  28.         // get all button then set a listener for general.
  29.         Button[] btns = { (Button) this.findViewById(R.id.button_num1),
  30.                 (Button) this.findViewById(R.id.button_num2),
  31.                 (Button) this.findViewById(R.id.button_num3),
  32.                 (Button) this.findViewById(R.id.button_num4),
  33.                 (Button) this.findViewById(R.id.button_num5),
  34.                 (Button) this.findViewById(R.id.button_num6),
  35.                 (Button) this.findViewById(R.id.button_num7),
  36.                 (Button) this.findViewById(R.id.button_num8),
  37.                 (Button) this.findViewById(R.id.button_num9),
  38.                 (Button) this.findViewById(R.id.button_plus),
  39.                 (Button) this.findViewById(R.id.button_sub) };
  40.  
  41.         OnClickListener generalOnClick = new OnClickListener() {
  42.             public void onClick(View v) {
  43.                 // set the txt of editText plus the text of button.
  44.                 edtxt_result.setText(edtxt_result.getText().toString()
  45.                         + ((Button) v).getText());
  46.             }
  47.         };
  48.  
  49.         for (Button btn : btns)
  50.             btn.setOnClickListener(generalOnClick);
  51.  
  52.         // calculate
  53.         btn_amount.setOnClickListener(new OnClickListener() {
  54.             public void onClick(View v) {
  55.                 
  56.                 // reverse string to create a tree which grow to right side
  57.                 String formula = new StringBuffer(edtxt_result.getText().toString()).reverse().toString();
  58.  
  59.                 Node root = new Node(), now = root;
  60.                 int last_index_ofSymbol = 0;
  61.                 
  62.                 for (int i = 0; i < formula.toCharArray().length; i++) {
  63.                     if (formula.toCharArray()[i] == '+' || formula.toCharArray()[i] == '-') {                        
  64.                         now.value = formula.toCharArray()[i] + "";
  65.                         now.right = new Node();
  66.                         if(last_index_ofSymbol==0)
  67.                             now.right.value = formula.substring(last_index_ofSymbol, i);
  68.                         else
  69.                             now.right.value = formula.substring(last_index_ofSymbol+1, i);
  70.                         last_index_ofSymbol = i;
  71.                         now.left = new Node();
  72.                         now = now.left;
  73.                     } else if (i == formula.toCharArray().length - 1) {
  74.                         now.value = formula.substring(last_index_ofSymbol+1);
  75.                     }
  76.                 }
  77.  
  78.                 // calculate by symbol.
  79.                 int result = 0;
  80.                 result = Node.inOrder(root);
  81.                 
  82.                 // plus the last num in stack.
  83.                 if (result < 0) {
  84.                     edtxt_result.setText("");
  85.                     edtxt_result.setHint("不支援負數計算");
  86.                 } else
  87.                     edtxt_result.setText(result + "");
  88.             }
  89.         });
  90.     }
  91. }
  92.  
  93. class Node {
  94.     public Node() {
  95.         value = "";
  96.         left = null;
  97.         right = null;
  98.     }
  99.  
  100.     String value;
  101.     Node left;
  102.     Node right;
  103.     
  104.     public static int inOrder(Node n){
  105.         if(n!=null){    
  106.             if(n.value.equals("+"))
  107.                 return inOrder(n.left) + inOrder(n.right);
  108.             else if(n.value.equals("-"))
  109.                 return inOrder(n.left) - inOrder(n.right);
  110.         }
  111.         return Integer.parseInt(n.value);
  112.     }
  113. }
本來以為樹狀結構的話程式碼可以少寫很多，結果根本也沒有，而且一開始向右生長的樹被我寫成向左生長，所以減法一直算錯，自己還在那裏想半天。
作者： 於
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1 則留言:

  1. 匿名2013年8月22日 上午11:28

    兄弟，我在研究您的Stack並且執行看看，

    但編譯器說明:

    int result = 0;
    while (!symbols.isEmpty()) {
    switch (symbols.pop()) {
    case '+':
    result += nums.pop();
    break;
    case '-':
    result -= nums.pop();
    break;
    }
    }

    此段程式碼有些錯誤，似乎是與INT、操作碼的錯誤!

    是不是型態類型有問題呢?

    回覆刪除

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