转换器与过滤器不同：转换器指定如何将文本转换为值，并且过滤器过滤器可以更改用户可能进行的操作。听起来两者都需要，但您希望过滤器更准确地过滤允许的更改。
我通常发现，如果更改被接受，则最容易检查文本的新值。您可以选择添加一个
-，后跟
1-9任意数量的数字。允许使用空字符串很重要，否则用户将无法删除所有内容。
所以你可能需要像
UnaryOperator<Change> integerFilter = change -> { String newText = change.getControlNewText(); if (newText.matches("-?([1-9][0-9]*)?")) { return change; } return null;};myNumericField.setTextFormatter( new TextFormatter<Integer>(new IntegerStringConverter(), 0, integerFilter));您甚至可以向过滤器添加更多功能，以使其
-以更智能的方式进行处理，例如
UnaryOperator<Change> integerFilter = change -> { String newText = change.getControlNewText(); // if proposed change results in a valid value, return change as-is: if (newText.matches("-?([1-9][0-9]*)?")) { return change; } else if ("-".equals(change.getText()) ) { // if user types or pastes a "-" in middle of current text, // toggle sign of value: if (change.getControlText().startsWith("-")) { // if we currently start with a "-", remove first character: change.setText(""); change.setRange(0, 1); // since we're deleting a character instead of adding one, // the caret position needs to move back one, instead of // moving forward one, so we modify the proposed change to // move the caret two places earlier than the proposed change: change.setCaretPosition(change.getCaretPosition()-2); change.setAnchor(change.getAnchor()-2); } else { // otherwise just insert at the beginning of the text: change.setRange(0, 0); } return change ; } // invalid change, veto it by returning null: return null;};这将使用户
-可以随时按下它，并且可以切换整数的符号。
SSCCE：
import java.util.function.UnaryOperator;import javafx.application.Application;import javafx.geometry.Pos;import javafx.scene.Scene;import javafx.scene.control.Button;import javafx.scene.control.TextField;import javafx.scene.control.TextFormatter;import javafx.scene.control.TextFormatter.Change;import javafx.scene.layout.VBox;import javafx.stage.Stage;import javafx.util.StringConverter;import javafx.util.converter.IntegerStringConverter;public class IntegerFieldExample extends Application { @Override public void start(Stage primaryStage) { TextField integerField = new TextField(); UnaryOperator<Change> integerFilter = change -> { String newText = change.getControlNewText(); if (newText.matches("-?([1-9][0-9]*)?")) { return change; } else if ("-".equals(change.getText()) ) { if (change.getControlText().startsWith("-")) { change.setText(""); change.setRange(0, 1); change.setCaretPosition(change.getCaretPosition()-2); change.setAnchor(change.getAnchor()-2); return change ; } else { change.setRange(0, 0); return change ; } } return null; }; // modified version of standard converter that evaluates an empty string // as zero instead of null: StringConverter<Integer> converter = new IntegerStringConverter() { @Override public Integer fromString(String s) { if (s.isEmpty()) return 0 ; return super.fromString(s); } }; TextFormatter<Integer> textFormatter = new TextFormatter<Integer>(converter, 0, integerFilter); integerField.setTextFormatter(textFormatter); // demo listener: textFormatter.valueProperty().addListener((obs, oldValue, newValue) -> System.out.println(newValue)); VBox root = new VBox(5, integerField, new Button("Click Me")); root.setAlignment(Pos.CENTER); Scene scene = new Scene(root, 300, 120); primaryStage.setScene(scene); primaryStage.show(); } public static void main(String[] args) { launch(args); }}
