我正在尝试编写一个javafx应用程序来观看系统剪贴板:
package sample;
import javafx.event.ActionEvent;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.util.Duration;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.scene.input.Clipboard;
import javafx.scene.input.ClipboardContent;
public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception{
primaryStage.show();
final Clipboard clipboard = Clipboard.getSystemClipboard();
final String oldString = "";
final String newString = "";
Timeline repeatTask = new Timeline(new KeyFrame(Duration.millis(200), new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
if (clipboard.hasString()) {
newString = clipboard.getString();
if(oldString != newString) {
System.out.printf("String changed in clipboard: " + newString);
oldString = newString;
}
else {
System.out.println("String not changed.");
}
}
}
}));
repeatTask.setCycleCount(Timeline.INDEFINITE);
repeatTask.play();
}
public static void main(String[] args) {
launch(args);
}
}
问题是我需要将剪贴板的旧内容存储在时间轴对象之外,我需要对它们进行更改,但是一旦它们设置为final - 就像java要求那样 - 不再可能进行修改。 / p>
答案 0 :(得分:2)
您可以将oldString
作为Application类的字段:
private String oldString = "";
@Override
public void start(Stage primaryStage) throws Exception {
primaryStage.show();
final Clipboard clipboard = Clipboard.getSystemClipboard();
Timeline repeatTask = new Timeline(new KeyFrame(Duration.millis(200), new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
if (clipboard.hasString()) {
String newString = clipboard.getString();
if(!oldString.equals(newString)) {
System.out.printf("String changed in clipboard: " + newString);
oldString = newString;
}
else {
System.out.println("String not changed.");
}
}
}
}));
repeatTask.setCycleCount(Timeline.INDEFINITE);
repeatTask.play();
}
这是有效的,因为当您访问oldString
时,您实际上正在访问this.oldString
,其中this
是最终的。
另请注意,要比较字符串,您应使用oldString.equals(newString)
而非比较对象标识(==
/ !=
)。
此外,如果您使用的是Java 8,则可以使用ReactFX删除Timeline样板:
private String oldString = "";
@Override
public void start(Stage primaryStage) throws Exception {
primaryStage.show();
final Clipboard clipboard = Clipboard.getSystemClipboard();
EventStreams.ticks(Duration.ofMillis(200)).subscribe(tick -> {
if (clipboard.hasString()) {
String newString = clipboard.getString();
if(!oldString.equals(newString)) {
System.out.printf("String changed in clipboard: " + newString);
oldString = newString;
}
else {
System.out.println("String not changed.");
}
}
});
}
有关使用ReactFX中的计时器的详细信息,请参阅我的博文http://tomasmikula.github.io/blog/2014/06/04/timers-in-javafx-and-reactfx.html