基于Java的計算器算法(源代碼)

importjava.awt.BorderLayout;importjava.awt.Color;importjava.awt.GridLayout;importjava.awt.event.ActionEvent;importjava.awt.event.ActionListener;importjavax.swing.JButton;importjavax.swing.JFrame;importjavax.swing.JPanel;importjavax.swing.JTextField;/***一個計算器，與Windows附件自帶計算器的標準版功能、界面相仿。但還不支持鍵盤操作。*/publicclassCalculatorextendsJFrameimplementsActionListener{/**計算器上的鍵的顯示名字*/privatefinalString[]KEYS={"7","8","9","/","sqrt","4","5","6","*","%","1","2","3","-","1/x","0","+/-",".","+","="};/**計算器上的功能鍵的顯示名字*/privatefinalString[]COMMAND={"Backspace","CE","C"};/**計算器左邊的M的顯示名字*/privatefinalString[]M={"","MC","MR","MS","M+"};/**計算器上鍵的按鈕*/privateJButtonkeys[]=newJButton[KEYS.length];/**計算器上的功能鍵的按鈕*/privateJButtoncommands[]=newJButton[COMMAND.length];/**計算器左邊的M的按鈕*/privateJButtonm[]=newJButton[M.length];/**計算結(jié)果文本框*/privateJTextFieldresultText=newJTextField("0");//標志用戶按的是否是整個表達式的第一個數(shù)字,或者是運算符后的第一個數(shù)字privatebooleanfirstDigit=true;//計算的中間結(jié)果。privatedoubleresultNum=0.0;//當前運算的運算符privateStringoperator="=";//操作是否合法privatebooleanoperateValidFlag=true;/***構(gòu)造函數(shù)*/publicCalculator(){super();//初始化計算器init();//設(shè)置計算器的背景顏色this.setBackground(Color.LIGHT_GRAY);this.setTitle("計算器");//在屏幕(500,300)坐標處顯示計算器this.setLocation(500,300);//不許修改計算器的大小this.setResizable(false);//使計算器中各組件大小合適this.pack();}/***初始化計算器*/privatevoidinit(){//文本框中的內(nèi)容采用右對齊方式resultText.setHorizontalAlignment(JTextField.RIGHT);//不允許修改結(jié)果文本框resultText.setEditable(false);//設(shè)置文本框背景顏色為白色resultText.setBackground(Color.white);//初始化計算器上鍵的按鈕，將鍵放在一個畫板內(nèi)JPanelcalckeysPanel=newJPanel();//用網(wǎng)格布局器，4行，5列的網(wǎng)格，網(wǎng)格之間的水平方向間隔為3個象素，垂直方向間隔為3個象素calckeysPanel.setLayout(newGridLayout(4,5,3,3));for(inti=0;i<KEYS.length;i++){keys[i]=newJButton(KEYS[i]);calckeysPanel.add(keys[i]);keys[i].setForeground(Color.blue);}//運算符鍵用紅色標示，其他鍵用藍色表示keys[3].setForeground(Color.red);keys[8].setForeground(Color.red);keys[13].setForeground(Color.red);keys[18].setForeground(Color.red);keys[19].setForeground(Color.red);//初始化功能鍵，都用紅色標示。將功能鍵放在一個畫板內(nèi)}/***處理運算符鍵被按下的事件**@paramkey*/privatevoidhandleOperator(Stringkey){if(operator.equals("/")){//除法運算//如果當前結(jié)果文本框中的值等于0if(getNumberFromText()==0.0){//操作不合法operateValidFlag=false;resultText.setText("除數(shù)不能為零");}else{resultNum/=getNumberFromText();}}elseif(operator.equals("1/x")){//倒數(shù)運算if(resultNum==0.0){//操作不合法operateValidFlag=false;resultText.setText("零沒有倒數(shù)");}else{resultNum=1/resultNum;}}elseif(operator.equals("+")){//加法運算resultNum+=getNumberFromText();}elseif(operator.equals("-")){//減法運算resultNum-=getNumberFromText();}elseif(operator.equals("*")){//乘法運算resultNum*=getNumberFromText();}elseif(operator.equals("sqrt")){//平方根運算resultNum=Math.sqrt(resultNum);}elseif(operator.equals("%")){//百分號運算，除以100resultNum=resultNum/100;}elseif(operator.equals("+/-")){//正數(shù)負數(shù)運算resultNum=resultNum*(-1);}elseif(operator.equals("=")){//賦值運算resultNum=getNumberFromText();}if(operateValidFlag){//雙精度浮點數(shù)的運算longt1;doublet2;t1=(long)resultNum;t2=resultNum-t1;if(t2==0){resultText.setText(String.valueOf(t1));}else{resultText.setText(String.valueOf(resultNum));}}//運算符等于用戶按的按鈕operator=key;firstDigit=true;operateValidFlag=true;}/***從結(jié)果文本框中獲取數(shù)字**@return*/privatedoublegetNumberFromText(){doubleresult=0;try{result=Double.valueOf(resultText.getText()).doubleValue();}catch(NumberFormatExceptione){