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java运算减法代码 java加减运算代码( 二 )

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}
// 对按钮进行反应的方法
public void actionPerformed(ActionEvent e)
{
JButton btn = (JButton)e.getSource();
if (btn == clear)
{
operation.setText("0");
dotExist = false;
storedNumber = 0;
lastOperator = '?';
}
else if (btn == equal)
{
operate('=');
equaled = true;
}
else if (btn == plus)
{
operate('+');
equaled = false;
}
else if (btn == minus)
{
operate('-');
equaled = false;
}
else if (btn == multi)
{
operate('*');
equaled = false;
}
else if (btn == div)
{
operate('/');
equaled = false;
}
else if (btn == changePN)
{
operate('p');
operate('=');
equaled = true;
}
else if (btn == sqrt)
{
operate('s');
operate('=');
equaled = true;
}
else
{
if (equaled)
storedNumber = 0;
for (int i = 0; i10; i++)
if (btn == numbers[i])
{
if (operation.getText().equals("0"))
operation.setText("" + i);
else if(! operated)
operation.setText(operation.getText() + i);
else
{
operation.setText("" + i);
operated = false;
}
}
if (btn == dot! dotExist)
{
operation.setText(operation.getText() + ".");
dotExist = true;
}
}
}
// 进行运算的方法
private void operate(char operator)
{
double currentNumber = Double.valueOf(operation.getText()).doubleValue();
if (lastOperator == '?')
storedNumber = currentNumber;
else if (lastOperator == '+')
storedNumber += currentNumber;
else if (lastOperator == '-')
storedNumber -= currentNumber;
else if (lastOperator == '*')
storedNumber *= currentNumber;
else if (lastOperator == '/')
storedNumber /= currentNumber;
else if (lastOperator == 'p')
storedNumber *= -1;
else if (lastOperator == 's')
storedNumber = Math.sqrt(currentNumber);
else if (lastOperator == '='equaled)
storedNumber = currentNumber;
operation.setText("" + storedNumber);
operated = true;
lastOperator = operator;
}
// 快捷使用GridBagLayout的方法
private void addComponent(GridBagLayout layout, Component component, int row, int col, int width, int height)
{
GridBagConstraints constraints = new GridBagConstraints();
constraints.fill = GridBagConstraints.BOTH;
constraints.insets = new Insets(10, 2, 10, 2);
constraints.weightx = 100;
constraints.weighty = 100;
constraints.gridx = col;
constraints.gridy = row;
constraints.gridwidth = width;
constraints.gridheight = height;
layout.setConstraints(component, constraints);
if (component instanceof JButton)
((JButton)component).addActionListener(this);
getContentPane().add(component);
}
// 主方法初始化并显示窗口
public static void main(String[] args)
{
Calculator calc = new Calculator();
calc.setSize(290, 400);
calc.setVisible(true);
}
}
java的加减乘除运算使用BigDecimal并且一定要用String来够造 。
实现方法如下：
import java.math.BigDecimal;
/**
* 由于Java的简单类型不能够精确的对浮点数进行运算，这个工具类提供精
【java运算减法代码 java加减运算代码】 * 确的浮点数运算，包括加减乘除和四舍五入 。
*/
public class Arith{
//默认除法运算精度
private static final int DEF_DIV_SCALE = 10;
//这个类不能实例化
private Arith(){
}
/**
* 提供精确的加法运算 。
* @param v1 被加数
* @param v2 加数
* @return 两个参数的和

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