だから私は電卓アプリを持っています。ビルドされ、正しく動作しますが、ユーザーがたとえば 4+√ を入力すると、エラーが発生します (以下を参照)。ユーザーが√ボタンを押したときにすでに操作を開始しているかどうかを確認する必要があり、完了している場合は何もしないでくださいと言われました。私はJavaに本当に慣れていないので、それを行う方法がわかりません。
これは、すべての計算が行われるアクション リスナーです (if (a.getSource() == textSqrt) が表示される場所の下にコードを配置する必要があると思います)。
public class event implements ActionListener {
public void actionPerformed(ActionEvent a) {
String text = a.getActionCommand();
if (text.equals("1")) {
result.setText(result.getText() + "1");
} else if (text.equals("2")) {
result.setText(result.getText() + "2");
} else if (text.equals("3")) {
result.setText(result.getText() + "3");
} else if (text.equals("4")) {
result.setText(result.getText() + "4");
} else if (text.equals("5")) {
result.setText(result.getText() + "5");
} else if (text.equals("6")) {
result.setText(result.getText() + "6");
} else if (text.equals("7")) {
result.setText(result.getText() + "7");
} else if (text.equals("8")) {
result.setText(result.getText() + "8");
} else if (text.equals("9")) {
result.setText(result.getText() + "9");
} else if (text.equals("0")) {
result.setText(result.getText() + "0");
} else if (result.getText().indexOf(".") < 1){
result.setText(result.getText() + ".");
}
String str = result.getText();
textBox = Double.parseDouble(str);
if (a.getSource()
== textAdd) {
op = 1;
firstInput = textBox;
result.setText("");
}
if (a.getSource()
== textSubtract) {
op = 2;
firstInput = textBox;
result.setText("");
}
if (a.getSource()
== textMultiply) {
op = 3;
firstInput = textBox;
result.setText("");
}
if (a.getSource()
== textDivide) {
op = 4;
firstInput = textBox;
result.setText("");
}
if (a.getSource()
== textPercent) {
op = 5;
firstInput = textBox;
result.setText("");
}
if (a.getSource() == textSqrt) {
op = 6;
firstInput = textBox;
answer = Math.sqrt(textBox);
str = Double.toString(answer);
result.setText(str);
}
if (a.getSource()
== textSign) {
double neg;
op = 7;
neg = 0 - textBox;
str = Double.toString(neg);
result.setText(str);
}
if (a.getSource()
== textEqual) {
if (op == 1) {
answer = firstInput + textBox;
str = Double.toString(answer);
result.setText(str);
} else if (op == 2) {
answer = firstInput - textBox;
str = Double.toString(answer);
result.setText(str);
} else if (op == 3) {
answer = firstInput * textBox;
str = Double.toString(answer);
result.setText(str);
} else if (op == 4) {
answer = firstInput / textBox;
str = Double.toString(answer);
result.setText(str);
} else if (op == 5) {
answer = firstInput % textBox;
str = Double.toString(answer);
result.setText(str);
}
}
}
}
操作と平方根ボタンを押したときに表示されるエラーは次のとおりです
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "."
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1241)
at java.lang.Double.parseDouble(Double.java:540)
at inlab05.InLab05$event.actionPerformed(InLab05.java:215)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:694)
at java.awt.EventQueue$3.run(EventQueue.java:692)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:708)
at java.awt.EventQueue$4.run(EventQueue.java:706)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
このような長い投稿で申し訳ありません。うまくいけば、誰かが私を助けることができます:)