效果图

image.png
注：未输入内容时显示Hint，获取到焦点以后自动清空Hint，失去焦点且内容为空时，再次显示Hint

代码实现

  1. import javafx.beans.value.ChangeListener;
  2. import javafx.beans.value.ObservableValue;
  3. import javafx.event.EventHandler;
  4. import javafx.scene.control.TextArea;
  5. import javafx.scene.input.KeyEvent;
  6. import javafx.scene.input.MouseEvent;
  8. public class HintTextArea extends TextArea {
  10.     private String mHint = "";
  12.     public HintTextArea(){
  13.         super();
  15.         this.setOnMouseClicked(new EventHandler<MouseEvent>() {
  16.             @Override
  17.             public void handle(MouseEvent event) {
  18.                 cleanHint();
  19.             }
  20.         });
  22.         this.setOnKeyPressed(new EventHandler<KeyEvent>() {
  23.             @Override
  24.             public void handle(KeyEvent event) {
  25.                 cleanHint();
  26.             }
  27.         });
  29.         this.focusedProperty().addListener(new ChangeListener<Boolean>() {
  30.             @Override
  31.             public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean newValue) {
  32.                 if (oldValue&&!newValue&&getLength()==0&&!mHint.isEmpty()){
  33.                     setHint(mHint);
  34.                 }
  35.             }
  36.         });
  37.     }
  39.     private void cleanHint(){
  40.         if (mHint.isEmpty()){
  41.             return;
  42.         }
  44.         if (getText().equals(mHint)){
  45.             clear();
  46.             setStyle("-fx-text-fill: #000000");
  47.         }
  48.     }
  51.     public void setHint(String hint){
  52.         this.mHint = hint;
  53.         this.setText(mHint);
  54.         this.setStyle("-fx-text-fill: #008B8B");
  55.     }
  56. }