java - 我想在我的 jframe 计算器中进行多次计算，例如 2+2+2

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我正在为学校项目制作一个 jFrame 计算器，但每当我尝试计算 2+2+2 之类的东西时，我都会得到 4。就像它只计算最后 2 位数字一样。有谁知道如何解决这一问题？这是我的代码

//numbers
private void NulNulActionPerformed(java.awt.event.ActionEvent evt) {                                       
Display.setText(Display.getText()+NulNul.getText());
}                                      

private void NulActionPerformed(java.awt.event.ActionEvent evt) {                                    
Display.setText(Display.getText()+Nul.getText());
}                                   

private void PuntActionPerformed(java.awt.event.ActionEvent evt) {                                     
if(PointClick == 0){
Display.setText(Display.getText()+Punt.getText());    
}
else{
    Punt.enable(false);

}
PointClick = 1;
}                                    

private void EenActionPerformed(java.awt.event.ActionEvent evt) {                                    
Display.setText(Display.getText()+Een.getText());
}                                   

private void TweeActionPerformed(java.awt.event.ActionEvent evt) {                                     
Display.setText(Display.getText()+Twee.getText());
}                                    

private void DrieActionPerformed(java.awt.event.ActionEvent evt) {                                     
Display.setText(Display.getText()+Drie.getText());
}                                    

private void VierActionPerformed(java.awt.event.ActionEvent evt) {                                     
Display.setText(Display.getText()+Vier.getText());
}                                    

private void VijfActionPerformed(java.awt.event.ActionEvent evt) {                                     
Display.setText(Display.getText()+Vijf.getText());
}                                    

private void ZesActionPerformed(java.awt.event.ActionEvent evt) {                                    
Display.setText(Display.getText()+Zes.getText());
}                                   

private void ZevenActionPerformed(java.awt.event.ActionEvent evt) {                                      
Display.setText(Display.getText()+Zeven.getText());
}                                     

private void AchtActionPerformed(java.awt.event.ActionEvent evt) {                                     
Display.setText(Display.getText()+Acht.getText());
}                                    

private void NegenActionPerformed(java.awt.event.ActionEvent evt) {                                      
Display.setText(Display.getText()+Negen.getText());
}                                     

//Clear
private void ClearActionPerformed(java.awt.event.ActionEvent evt) {                                      
Display.setText("");
PointClick = 0;
}                                     

//Back
private void BackActionPerformed(java.awt.event.ActionEvent evt) {                                     
String text;
text = Display.getText();
int len = text.length();
text = text.substring(0, len-1);
Display.setText(text);
}                                    

private void PlusActionPerformed(java.awt.event.ActionEvent evt) {                                     
firstnumber = Double.parseDouble(Display.getText());
Display.setText("");
PlusClick= 1;
MinusClick = MultiplyClick = DivideClick = PercentClick = PowerClick = PointClick = 0;
}                                    

private void EqualsActionPerformed(java.awt.event.ActionEvent evt) {                                       
secondnumber = Double.parseDouble(Display.getText());
if(PlusClick > 0){
    Result = firstnumber + secondnumber;
    Display.setText(String.valueOf(Result));
}
else if(MinusClick > 0){
    Result = firstnumber - secondnumber;
Display.setText(String.valueOf(Result));
}
else if(MultiplyClick > 0){
    Result = firstnumber * secondnumber;
Display.setText(String.valueOf(Result));
}
else if(DivideClick > 0){
    Result = firstnumber / secondnumber;
Display.setText(String.valueOf(Result));
}
else if(PowerClick > 0){
    for(int i=1;i<=secondnumber;i++)
    {
        Result = Result * firstnumber;
    } 
Display.setText(String.valueOf(Result));    
}
else if(PercentClick > 0){
    Result = (firstnumber * secondnumber) / 100;
Display.setText(String.valueOf(Result));    
}
}                                      

private void MinActionPerformed(java.awt.event.ActionEvent evt) {                                    
firstnumber = Double.parseDouble(Display.getText());
Display.setText("");
MinusClick= 1;
PlusClick = MultiplyClick = DivideClick = PercentClick = PowerClick = PointClick = 0;
}                                   

private void KeerActionPerformed(java.awt.event.ActionEvent evt) {                                     
firstnumber = Double.parseDouble(Display.getText());
Display.setText("");
MultiplyClick= 1;
MinusClick = PlusClick = DivideClick = PercentClick = PowerClick = PointClick = 0;
}                                    

private void DelenActionPerformed(java.awt.event.ActionEvent evt) {                                      
firstnumber = Double.parseDouble(Display.getText());
Display.setText("");
DivideClick= 1;
MinusClick = MultiplyClick = PlusClick = PercentClick = PowerClick = PointClick = 0;
}                                     

private void WortelActionPerformed(java.awt.event.ActionEvent evt) {                                       
firstnumber = Double.parseDouble(Display.getText());
Display.setText(String.valueOf(Math.sqrt(firstnumber)));
}                                      

private void PIActionPerformed(java.awt.event.ActionEvent evt) {                                   
Display.setText(String.valueOf(Math.PI));
}                                  

private void MachtActionPerformed(java.awt.event.ActionEvent evt) {                                      
firstnumber = Double.parseDouble(Display.getText());
Display.setText("");
PowerClick= 1;
MinusClick = MultiplyClick = PlusClick = PercentClick = DivideClick = PointClick = 0;
}                                     

private void ProcentActionPerformed(java.awt.event.ActionEvent evt) {                                        
firstnumber = Double.parseDouble(Display.getText());
Display.setText("");
PercentClick= 1;
MinusClick = MultiplyClick = PlusClick = PowerClick = DivideClick = PointClick = 0;
}                                       

private void InverseActionPerformed(java.awt.event.ActionEvent evt) {                                        
firstnumber = Double.parseDouble(Display.getText());
Display.setText(String.valueOf(1 / firstnumber));
}                                       

private void PlusminusActionPerformed(java.awt.event.ActionEvent evt) {                                          
firstnumber = Double.parseDouble(Display.getText());
Display.setText(String.valueOf((-1) * firstnumber));
}                                         

Answer 1

它确实只计算最后 2 位数字，因为您不存储任何前面的数字。为了清楚起见，我们将示例设为 2+3+4。您的步骤是:

1. 阅读 2
2. 读取 +，将 2 存储为 firstnumber
3. 阅读 3
4. 读取 +，将 3 存储为 firstnumber(覆盖我们之前的值)
5. 阅读 4
6. 读取=，将4存储为第二个数字，计算第一个数字 + 第二个数字

使用您的方法，您应该做的是在步骤 4 中计算“子结果”(如果需要，在接下来的步骤中)并将其存储在 firstnumber 变量中。