b0 = new Button("0");
b1 = new Button("1");
b2 = new Button("2");
b3 = new Button("3");
b4 = new Button("4");
b5 = new Button("5");
b6 = new Button("6");
b7 = new Button("7");
b8 = new Button("8");
b9 = new Button("9");
bPoint = new Button(".");
bAdd = new Button("+");
bDec = new Button("-");
bMul = new Button("*");
bDiv = new Button("/");
bCal = new Button("=");
b0.addActionListener(new setLabelText_ActionListener());
b1.addActionListener(new setLabelText_ActionListener());
b2.addActionListener(new setLabelText_ActionListener());
b3.addActionListener(new setLabelText_ActionListener());
b4.addActionListener(new setLabelText_ActionListener());
b5.addActionListener(new setLabelText_ActionListener());
b6.addActionListener(new setLabelText_ActionListener());
b7.addActionListener(new setLabelText_ActionListener());
b8.addActionListener(new setLabelText_ActionListener());
b9.addActionListener(new setLabelText_ActionListener());
bPoint.addActionListener(new setLabelText_ActionListener());
bAdd.addActionListener(new setOperator_ActionListener());
bDec.addActionListener(new setOperator_ActionListener());
bMul.addActionListener(new setOperator_ActionListener());
bDiv.addActionListener(new setOperator_ActionListener());
bCal.addActionListener(new setOperator_ActionListener());

class setLabelText_ActionListener implements ActionListener{
public void actionPerformed(ActionEvent e){
Button tempB = (Button)e.getSource(); //e.getSource();这个函数是什么意思？我可以理解我我按了一个数字比如6，然后就把6付给tempB这个按钮吗？
s = tempB.getLabel();
setTextFieldText(); 按3就显示3的函数
}
}

class setOperator_ActionListener implements ActionListener{
public void actionPerformed(ActionEvent e){
Button tempB = (Button)e.getSource();
op = tempB.getLabel();
if(op.equals("+")){
tf.setText(cal.opAdd(tf.getText()));
ifOp = true;
}else if(op.equals("-")){
tf.setText(cal.opSubtract(tf.getText()));
ifOp = true;
}else if(op.equals("*")){
tf.setText(cal.opMultiply(tf.getText()));
ifOp = true;
}else if(op.equals("/")){
tf.setText(cal.opDivide(tf.getText()));
ifOp = true;
}else if(op.equals("=")){
tf.setText(cal.opEquals(tf.getText()));
ifOp = true;
}
}
}
}
private void operate(String x){
double x1 = stringToDouble(x); //把字符串转换成字符的函数
double y = stringToDouble(result);
switch (op){                  //op的初始值为0
case 0:
result = x;
break;
case 1:
result = String.valueOf(y+x1);
break;
case 2:
result = String.valueOf(y-x1);
break;
case 3:
result = String.valueOf(y*x1);
break;
case 4:
if(x1!=0){
result = String.valueOf(y/x1);
}
else{
result = "The divisor can't be zero!";
}
break;
}
}
public String opAdd(String x){
operate(x);
op = add;
return result;
}
我截取了这三段程序提个问题  例如在计算器上要算3+5
当在计算器上按3的时候就显示3当按+的时候就执行setOperator_ActionListener 大家可以沿着函数看
在opAdd函数中只执行了一遍operate(x)就我理解执行完这里result就是3再执行下去result也还是3啊怎么会是8呢？应该有两个operate才对啊？？？？？
我不知道说清楚没有，希望大家看看到底怎么出的结果啊。程序中其它部分与计算无关就不写出来了

确实没说清楚 起码加些标点啊

e.getSource();这个函数是得到你点击按钮对象的引用，通过这个引用来调用方法来得到该按钮上的标签。