这个异常处理能讲解下吗，看不懂啊

Question

btEqual.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				ScriptEngineManager manager = new ScriptEngineManager();				ScriptEngine SE = manager.getEngineByName("js");				String string = new String(showExpression.getText());				try {					String ans = SE.eval(string).toString();					showExpression.setText(ans);				} catch (Exception e) {					// TODO: handle exception					showExpression.setText("ERROR!");				}			}		});

btEqual.setOnAction(new EventHandler<ActionEvent>() { @Override public void handle(ActionEvent event) { ScriptEngineManager manager = new

import javafx.application.Application;import javafx.event.ActionEvent;import javafx.event.EventHandler;import javafx.geometry.Insets;import javafx.scene.Scene;import javafx.scene.control.Button;import javafx.scene.control.TextField;import javafx.scene.image.Image;import javafx.scene.image.ImageView;import javafx.scene.layout.BorderPane;import javafx.scene.layout.HBox;import javafx.stage.Stage;import javax.script.ScriptEngine;import javax.script.ScriptEngineManager;import javax.script.ScriptException;public class Main extends Application {	@Override	public void start(Stage primaryStage) throws Exception {		// 获取带图片的按钮		Button bt0 = new Button("", new ImageView(new Image("images/0.png")));		Button bt1 = new Button("", new ImageView(new Image("images/1.png")));		Button bt2 = new Button("", new ImageView(new Image("images/2.png")));		Button bt3 = new Button("", new ImageView(new Image("images/3.png")));		Button bt4 = new Button("", new ImageView(new Image("images/4.png")));		Button bt5 = new Button("", new ImageView(new Image("images/5.png")));		Button bt6 = new Button("", new ImageView(new Image("images/6.png")));		Button bt7 = new Button("", new ImageView(new Image("images/7.png")));		Button bt8 = new Button("", new ImageView(new Image("images/8.png")));		Button bt9 = new Button("", new ImageView(new Image("images/9.png")));		Button btAdd = new Button("", new ImageView(new Image("images/ADD.png")));		Button btMinus = new Button("", new ImageView(new Image("images/MINUS.png")));		Button btMultiply = new Button("", new ImageView(new Image("images/MULTIPLY.png")));		Button btDivide = new Button("", new ImageView(new Image("images/DIVIDE.png")));		Button btEqual = new Button("", new ImageView(new Image("images/EQUAL.png")));		Button btLeft = new Button("", new ImageView(new Image("images/LEFT_PAREN.png")));		Button btRight = new Button("", new ImageView(new Image("images/RIGHT_PAREN.png")));		Button btPoint = new Button("", new ImageView(new Image("images/POINT.png")));		Button btClear = new Button("", new ImageView(new Image("images/CLEAR.png")));		Button btBack = new Button("", new ImageView(new Image("images/BACK.png")));		// 因为BorderPane最多只能有三水平行，所以用一个BorderPane作为主面板		// 再用两个BorderPane嵌入到主面板中，这两个BorderPane正好可以装满所有要用到的子节点		BorderPane pane = new BorderPane(); // 主面板，用来放pane1，pane2		BorderPane pane1 = new BorderPane(); // 放琐碎的Node的pane1		BorderPane pane2 = new BorderPane(); // 放琐碎的Node的pane2		// Hbox1 Hbox2 Hbox3放到pane1中		HBox hBox1 = new HBox(5);		HBox hBox2 = new HBox(5);		HBox hBox3 = new HBox(5);		// Hbox4,5,6放到pane2中		HBox hBox4 = new HBox(5);		HBox hBox5 = new HBox(5);		HBox hBox6 = new HBox(5);		// 显示输入的文本框		TextField showExpression = new TextField();		showExpression.setPrefSize(280, 40);		/*		 * 下面开始放pane1中的节点，		 */		hBox1.getChildren().add(showExpression);		hBox2.getChildren().addAll(btClear, btBack, btPoint, btDivide);		hBox3.getChildren().addAll(bt7, bt8, bt9, btMultiply);		hBox1.setPadding(new Insets(15, 15, 0, 27));		hBox2.setPadding(new Insets(15, 15, 0, 30));		hBox3.setPadding(new Insets(15, 15, 5, 30));		pane1.setTop(hBox1);		pane1.setCenter(hBox2);		pane1.setBottom(hBox3);		// 接着把pane1放到pane的top中		pane.setTop(pane1);		/*		 * 下面开始放pane2中的节点		 */		// 运行过程中发现左右括号的图片太小了，不太美观，调整一下		btLeft.setPadding(new Insets(11, 11, 11, 5));		btRight.setPadding(new Insets(11, 11, 11, 5));		hBox4.getChildren().addAll(bt4, bt5, bt6, btMinus);		hBox5.getChildren().addAll(bt1, bt2, bt3, btAdd);		hBox6.getChildren().addAll(bt0, btLeft, btRight, btEqual);		hBox4.setPadding(new Insets(15, 15, 0, 30));		hBox5.setPadding(new Insets(15, 15, 0, 30));		hBox6.setPadding(new Insets(15, 15, 10, 30));		pane2.setTop(hBox4);		pane2.setCenter(hBox5);		pane2.setBottom(hBox6);		// 接着把pane1放到pane的Center中		pane.setCenter(pane2);		/*为每一个按钮《添加事件》		 * 下面开始对每个按钮添加事件		 * 即bt变量按钮设置一个事件，重写handle逻辑操作代码，获取到对应的值		 * showExpression.setText(string); 设置值为（字符串）当你点击button2的时候，button2的内容会变成Accepted。到时候调用js引擎对字符串进行eval（）操作		 *		 */		//下面开始对每个按钮添加事件		bt1.setOnAction(new EventHandler<ActionEvent>() {			//重写handle方法			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "1";				showExpression.setText(string);			}		});		bt2.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "2";				showExpression.setText(string);			}		});		bt3.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "3";				showExpression.setText(string);			}		});		bt4.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "4";				showExpression.setText(string);			}		});		bt5.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "5";				showExpression.setText(string);			}		});		bt6.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "6";				showExpression.setText(string);			}		});		bt7.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "7";				showExpression.setText(string);			}		});		bt8.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "8";				showExpression.setText(string);			}		});		bt9.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "9";				showExpression.setText(string);			}		});		bt0.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "0";				showExpression.setText(string);			}		});		btLeft.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "(";				showExpression.setText(string);			}		});		btRight.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += ")";				showExpression.setText(string);			}		});		btPoint.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += ".";				showExpression.setText(string);			}		});		btBack.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string = string.substring(0, string.length() - 1);				showExpression.setText(string);			}		});		btAdd.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "+";				showExpression.setText(string);			}		});		btMinus.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "-";				showExpression.setText(string);			}		});		btMultiply.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "*";				showExpression.setText(string);			}		});		btDivide.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				String string = new String(showExpression.getText());				string += "/";				showExpression.setText(string);			}		});		btClear.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				showExpression.setText("");			}		});		/*		 * 使用JS计算引擎得出结果		 */		btEqual.setOnAction(new EventHandler<ActionEvent>() {			@Override			public void handle(ActionEvent event) {				ScriptEngineManager manager = new ScriptEngineManager();				ScriptEngine SE = manager.getEngineByName("js");				String string = new String(showExpression.getText());				try {					String ans = SE.eval(string).toString();					showExpression.setText(ans);				} catch (Exception e) {					// TODO: handle exception					showExpression.setText("ERROR!");				}			}		});		Scene scene = new Scene(pane);		primaryStage.setTitle("Calculator");		primaryStage.setScene(scene);		primaryStage.show();	}

ScriptEngineManager(); ScriptEngine SE = manager.getEngineByName("js"); String string = new String(showExpression.getText()); try { String ans = SE.eval(string).toString(); showExpression.setText(ans); } catch (Exception e) { // TODO: handle exception showExpression.setText("ERROR!"); } } });

Answer 1

你是要解释代码吧，你这个并不是异常提示信息。