java 如何在 onAction 方法中从 TextField 获取文本？
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How to get text from TextField in onAction method?
提问by woyaru
I am getting NullPointerException when I am trying to get text from TextFieldin one of my Buttonon action method. This is my textField definition:
当我尝试从TextField我的一种Buttonon action 方法中获取文本时，我收到 NullPointerException 。这是我的 textField 定义：
TextField textField = new TextField();
textField.setPromptText("Some text");
GridPane.setMargin(textField, new Insets(50, 50, 10, 50));
gridPane.add(textField, 0, 0);
And this is my button with its on action method:
这是我的按钮及其 on action 方法：
Button button = new Button("Button");
GridPane.setMargin(button , new Insets(0, 50, 0, 50));
gridPane.add(button , 0, 1);
button.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
String text = textField.getText();
}
});
I am getting NullPointerExcpetionin this line: String text = textField.getText();. How can I get text from textField in onAction method?
我进入NullPointerExcpetion这一行：String text = textField.getText();。如何在 onAction 方法中从 textField 获取文本？
采纳答案by Reimeus
One possibility is that you are shadowing your TextFieldin a method or constructor. This appears to be a possibility given that the local variable has not been declared as final.
If your EventHandleris using a class member variable called textField, then replace
一种可能性是您TextField在方法或构造函数中隐藏了您的方法。鉴于局部变量尚未声明为 ，这似乎是一种可能性final。如果您EventHandler使用的是名为 的类成员变量textField，则替换
TextField textField = new TextField();
with
和
textField = new TextField();
