JAVAFX-標簽字段未在動作事件處理程序上更新

Question

我是JAVAFX的新手。 我在JavaFx應用程序中有一個登錄表單。 它具有在fxml文件中定義的Label字段，其文本值是在使用不同消息進行身份驗證之后設置的。 請參見下面的代碼。

碼

if(userid>0){ 
    //the below setText call doesn't work and update the UI
    actiontarget.setText("Modems are initializing. It may take longer time... ");
    bootstrap =new Bootstrap();
    new Thread(){
        public void run(){
            bootstrap.run();
        }
    }.start();  
    while(!bootstrap.isSet()){
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        // the below call also doesn't work
        actiontarget.setText("Modems are getting initialized. Please wait for sometime..");
    }
    serialModemList=bootstrap.getSerialModemList();
    getPanelList(serialModemList);

}else{
    // this one method call works fine. not sure why?
    actiontarget.setText("Invalid Terminal and Password ");
}

用戶有效時，調用actiontarget.setText(..)無效。 但是，如果用戶輸入無效的憑據，它就可以工作。 請讓我知道代碼有什么問題。

XML文件

<?xml version="1.0" encoding="UTF-8"?>

<?import java.net.*?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.text.*?>
<?import javafx.scene.image.*?>

<BorderPane maxHeight="-Infinity" maxWidth="-Infinity"
    minHeight="-Infinity" minWidth="-Infinity" prefHeight="469.0"
    prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.40" xmlns:fx="http://javafx.com/fxml/1">
    <center>

        <GridPane fx:id="gridpane" xmlns:fx="http://javafx.com/fxml"
            alignment="center" hgap="10" vgap="10">

            <Text text="Welcome" GridPane.columnIndex="0" GridPane.rowIndex="0"
                GridPane.columnSpan="2" />

            <Label text="Terminal" GridPane.columnIndex="0"
                GridPane.rowIndex="1">
                <font>
                    <Font size="15.0" />
                </font>
            </Label>

            <TextField fx:id="txtuser" GridPane.columnIndex="1"
                GridPane.rowIndex="1" />

            <Label text="Password" GridPane.columnIndex="0"
                GridPane.rowIndex="2">
                <font>
                    <Font size="15.0" />
                </font>
            </Label>
            <PasswordField fx:id="txtaun" GridPane.columnIndex="1"
                GridPane.rowIndex="2" />
            <HBox spacing="10" alignment="bottom_right"
                GridPane.columnIndex="1" GridPane.rowIndex="4">
                <Button fx:id="loginbtn" onAction="#handleLoginAction" text="LOGIN" />
            </HBox>
            <Label fx:id="message" GridPane.columnIndex="1"
                GridPane.rowIndex="6" />
            <Label fx:id="actiontarget" GridPane.columnIndex="1"
                GridPane.rowIndex="7" />
        </GridPane>
    </center>
    <top>
        <Label id="Header" minWidth="400.0" prefHeight="81.0" prefWidth="174.0"
            text="Sim Manager" BorderPane.alignment="CENTER">
            <font>
                <Font size="50.0" />
            </font>
        </Label>
    </top>
    <bottom>
        <Label prefHeight="69.0" prefWidth="126.0" text="Powered by CIAR"
            textFill="#20209e" BorderPane.alignment="bottom_right" />
    </bottom> 
</BorderPane>

請讓我知道是否需要任何信息。

Answer 1

我相信您的問題是使用Thread.sleep暫停了UI線程，這使其無法更新顯示。

嘗試使用Task （ https://docs.oracle.com/javafx/2/threads/jfxpub-threads.htm ）並在onSucceeded和onFailed設置文本。