[英]getting the buttons in a gridPane and change their text using javaFx
我試圖在我的控制器類中獲取gridPane的所有成員(它們是按鈕),但是我遇到了異常,您可以在下面看到它:
Exception in Application start methodjava.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$152(LauncherImpl.java:182)
at com.sun.javafx.application.LauncherImpl$$Lambda$51/1263764.run(Unknown Source)
at java.lang.Thread.run(Thread.java:745)
Caused by: javafx.fxml.LoadException:
file:/C:/Users/Family/Documents/NetBeansProjects/FarsiCallender/dist/run1583526066/FarsiCallender.jar!/farsicallender/FXMLDocument.fxml
at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2605)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2583)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2445)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3218)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3179)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3152)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3128)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3108)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3101)
at farsicallender.FarsiCallender.start(FarsiCallender.java:29)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$159(LauncherImpl.java:863)
at com.sun.javafx.application.LauncherImpl$$Lambda$54/4239053.run(Unknown Source)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$172(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl$$Lambda$47/20085625.run(Unknown Source)
at com.sun.javafx.application.PlatformImpl.lambda$null$170(PlatformImpl.java:295)
at com.sun.javafx.application.PlatformImpl$$Lambda$49/3796086.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(PlatformImpl.java:294)
at com.sun.javafx.application.PlatformImpl$$Lambda$48/2900468.run(Unknown Source)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$145(WinApplication.java:101)
at com.sun.glass.ui.win.WinApplication$$Lambda$37/17230114.run(Unknown Source)
... 1 more
Caused by: java.lang.NullPointerException
at farsicallender.FXMLDocumentController.setDays(FXMLDocumentController.java:249)
at farsicallender.FXMLDocumentController.initialize(FXMLDocumentController.java:181)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2552)
... 22 more
Exception running application farsicallender.FarsiCallender
Java Result: 1
此異常來自我的代碼的這一部分,在檢查我的代碼之前,您必須知道我有gridPane(6 * 7),這是我的代碼:
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 7; j++) {
for (Node node : grid.getChildren()) {
if (grid.getRowIndex(node) == i && grid.getColumnIndex(node) == j) {
Button b = (Button)node;
b.setText(ar[i][j]+"");
System.out.println("z:" + i+" "+j);
break;
}
}
}
}
249行是:
if (grid.getRowIndex(node) == i && grid.getColumnIndex(node) == j) {
順便說一句,您不應從非靜態上下文中調用靜態方法。 您的IDE應對此發出警告。 但是你應該使用
GridPane.getRowIndex(node)
不
grid.getRowIndex(node)
等等
方法GridPane.getRowIndex(Node)
和GridPane.getColumnIndex(node)
返回包裝器Integer
對象,而不是原始int
。 因此,當您使用==
進行身份比較時,您將隱式使用拆箱。 換句話說,您的代碼相當於
if (GridPane.getRowIndex(node).intValue() == i
&& GridPane.getColumnIndex(node).intValue() == j) { ... }
如果有任何節點添加到網格窗格中,但未指定行索引和列索引,則GridPane.getRowIndex(...)
或GridPane.getColumnIndex(...)
將返回null,因此您將隱式嘗試調用intValue()
在空引用上,導致空指針異常。 請注意,如果已調用grid.setGridLinesVisible(true);
,這將導致GridPane
添加沒有設置行索引或列索引的節點。
因此,此方法的快速解決方案是執行空檢查:
Integer rowIndex = GridPane.getRowIndex(node);
Integer columnIndex = GridPane.getColumnIndex(node);
if (rowIndex != null && rowIndex.intValue() == i
&& columnIndex != null && columnIndex.intValue() == j) {
// ...
}
我可能更喜歡組織代碼,以便將按鈕保存在數組中,這樣就可以在沒有所有迭代的情況下訪問它們,但是我想這只是樣式問題。
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