android - 具有多种操作的简单计算器 - Android

Question

我创建了一个简单的计算器来计算两个输入(例如 2 + 2 = 4)。我现在想做的是让应用程序计算多个操作，例如(例如 2 + 2 * 4 - 1 = 15)。有人可以帮我处理我的代码吗？这是我的代码。

public class MainActivity extends Activity {

public String str ="";

 Character op = 'q';
 int i,num,numtemp;
    EditText showResult;
    String displayStr = "";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);

        showResult = (EditText)findViewById(R.id.result_id);


    }
      public void btn1Clicked(View v){
       insert(1);

      }

 public void btn2Clicked(View v){
       insert(2);

      }
      public void btn3Clicked(View v){
       insert(3);

      }
      public void btn4Clicked(View v){
       insert(4);

      }
      public void btn5Clicked(View v){
       insert(5);

      }
      public void btn6Clicked(View v){
       insert(6);
      }
      public void btn7Clicked(View v){
       insert(7);

      }
      public void btn8Clicked(View v){
       insert(8);

      }
      public void btn9Clicked(View v){
       insert(9);

      }

      public void btn0Clicked(View v){
           insert(0);

          }


      public void btnplusClicked(View v){
       perform();
       op = '+';
       displayStr += "+";
      }

 public void btnminusClicked(View v){
     perform();
        op = '-';
        displayStr += "-";    

      }
      public void btndivideClicked(View v){
       perform();
       op = '/';
       displayStr += "/";
      }
      public void btnmultiClicked(View v){
       perform();
       op = '*';
       displayStr += "*";
      }
      public void btnequalClicked(View v){
       calculate();

      }

 public void btnclearClicked(View v){
       reset();
      }
      private void reset() {
  // TODO Auto-generated method stub
   str ="";
   op ='q';
   num = 0;
   numtemp = 0;
   displayStr = "";
   showResult.setText("");
 }
 private void insert(int j) {
    // TODO Auto-generated method stub
       str = str+Integer.toString(j);
       num = Integer.valueOf(str).intValue();

       displayStr += Integer.toString(j); 
       showResult.setText(displayStr);

   }
      private void perform() {
    // TODO Auto-generated method stub
    str = "";
    numtemp = num;
   }
      private void calculate() {
    // TODO Auto-generated method stub
        String first=String.valueOf(numtemp);
     String second=String.valueOf(num);

          if(op == '+')
     num = numtemp+num;
    else if(op == '-')
     num = numtemp-num;
    else if(op == '/')
     num = numtemp/num;
    else if(op == '*')
     num = numtemp*num;
showResult.setText(first+op+second+"="+num);
   }

}

Answer 1

使用一些堆栈操作。
可能以下链接会对您有所帮助。

http://innovativenetsolutions.com/2013/01/calculator-app/
http://www.androiddom.com/2011/04/creating-android-calculator-tutorial.html