Question

我写过一个程序＆amp;我为它构建了一个GUI。当我尝试运行它时，它会引发异常NumberFormatException，这就是我得到的全部内容：

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
    at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
    at sun.misc.FloatingDecimal.parseDouble(Unknown Source)
    at java.lang.Double.parseDouble(Unknown Source)
    at newtp.GUI$2.actionPerformed(GUI.java:219)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$400(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

那么我该怎么办才能解决我的问题？

Answer 1

你的问题是你的字符串是空的

java.lang.NumberFormatException: empty String at

要解决此问题，您应该使用数字的字符串表示填充字符串（例如，字符串为3，双字符为7.7）

如果您向我们展示您的代码以查看问题所在，那将是最好的。

示例：

如果您执行以下操作

String string1 = "";
int int1 = Integer.parseInt(string1);

您将收到您收到的异常，因为Java无法为空字符串找到匹配的int值。

如果你这样做

String string2 = "3";
int int2 = Integer.parseInt(string2);

你不会收到异常，但是一个名为int2的变量包含值3。

Answer 2

正如Phiwa所说，一个解决方案就是不要传入一个空字符串。但是，处理这个问题可能更好。

如果输入的值不是正确的类型，您可以使用类似的内容来指定默认值：

int x;
try {
    //whatever you're doing to parse the string...probably x = Integer.parseInt("32"); or something
catch(NumberFormatException e) {
    e.printStackTrace();
    x = 12; //or whatever default value you want
}

Answer 3

当它变为空时，我已经将变量输出，这是在actionListener中，所以我带来了值（使用textField.getText（）;）解析完成了...我忘记引入所有的方法.. 感谢帮助家伙：）））

将字符串解析为double / integer时如何解决NumberFormatException

3 个答案: