安卓计算器，如何代码实现在文本框也把运算符显示出来？

[hello2013year]

我越来越笨了，想实现比如：输入数字的时候，再按下运算符按钮，把运算符也显示到 EditText里。如：3+2,然后按 =号按钮出结果。

package com.qinguo.myfirstapp;

import java.text.BreakIterator;

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;

public class BusOne extends Activity {
	private Button[] bnNum = new Button[11];
	private Button[] bnCommand = new Button[5];
	private EditText editText = null;
	private Button bnClear = null;
	private String lastCommand;
	private boolean clearFlag;
	private boolean firstFlag;
	private double result;

	public BusOne() {
		// 初始化各项值
		result = 0; // x的值
		firstFlag = true; // 是首次运算
		clearFlag = false; // 不需要清空
		lastCommand = "="; // 运算符
	}

	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		bnCommand[0] = (Button) findViewById(R.id.add);
		bnCommand[1] = (Button) findViewById(R.id.subtract);
		bnCommand[2] = (Button) findViewById(R.id.divide);
		bnCommand[3] = (Button) findViewById(R.id.equal);
		bnCommand[4] = (Button) findViewById(R.id.multiply);

		bnNum[0] = (Button) findViewById(R.id.num0);
		bnNum[1] = (Button) findViewById(R.id.num1);
		bnNum[2] = (Button) findViewById(R.id.num2);
		bnNum[3] = (Button) findViewById(R.id.num3);
		bnNum[4] = (Button) findViewById(R.id.num4);
		bnNum[5] = (Button) findViewById(R.id.num5);
		bnNum[6] = (Button) findViewById(R.id.num6);
		bnNum[7] = (Button) findViewById(R.id.num7);
		bnNum[8] = (Button) findViewById(R.id.num8);
		bnNum[9] = (Button) findViewById(R.id.num9);
		bnNum[10] = (Button) findViewById(R.id.point);
		editText = (EditText) findViewById(R.id.result);
		editText.setText("");
		NumberAction na = new NumberAction();
		CommandAction ca = new CommandAction();
		for (Button bc : bnCommand) {
			bc.setOnClickListener(ca);
		}
		for (Button bc : bnNum) {
			bc.setOnClickListener(na);
		}
		bnClear = (Button) findViewById(R.id.clear);
		bnClear.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View view) {
				editText.setText("");
				result = 0;
				firstFlag = true;
				clearFlag = false;
				lastCommand = "=";
			}
		});
	}
    
	private class NumberAction implements OnClickListener {

		@Override
		public void onClick(View view) {
			Button bn = (Button) view;
			String input = bn.getText().toString();
			if (firstFlag) {
				if (input.equals(".")) {
					return;
					
				}
				if (editText.getText().toString().equals("0.0")) {
					editText.setText("");
				}
				firstFlag = false;
			} else {
				String editTextStr = editText.getText().toString();
				if (editTextStr.indexOf(".") != -1 && input.equals(".")) {
					return;
				}
				if (editTextStr.equals("-") && input.equals(".")) {
					return;
				}
				/*if (editTextStr.equals("0") && !input.equals(".")) {
					return;
				}*/

			}
			if (clearFlag) {
				editText.setText("");
				clearFlag = false;
			}
			editText.setText(editText.getText().toString() + input);
		}

	}

	private class CommandAction implements OnClickListener {
		public void onClick(View view) {
			Button bn = (Button) view;
			String inputCommand = (String) bn.getText();
			if (firstFlag) {
				if (inputCommand.equals("-")) {
					editText.setText("-");
					firstFlag = true;
					
				}
			}else {
				if(!clearFlag){
					calculate(Double.parseDouble(editText.getText().toString()));
				}
				lastCommand = inputCommand;
				clearFlag = true;
			}
			
		}
	}
    
	
	private void calculate (double x ){
		if(lastCommand.equals("+")){
			result += x;
		}else if (lastCommand.equals("-")){
			result -= x;
		}else if (lastCommand.equals("*")){
			result *= x;
		}else if (lastCommand.equals("/")){
			result /= x;
		}else if (lastCommand.equals("=")){
			result = x;
		}
		editText.setText(""+result);
	}
}

[微笑面具]

这是完善后的代码么？