如何做交友网站今日热搜头条
目录
题目：*16.13（比较不同利率的贷款）
习题思路
代码示例
结果展示
题目：*16.13（比较不同利率的贷款）
改写编程练习题5.21，创建一个图形用户界面，如图16-41b所示。程序应该允许用户从文本域输入贷款额以及以年为单位的贷款年限，在文本域中会显示关于每种利率的月偿还额和总偿还额，利率从5%到8%，按1/8（0.125%）递增。
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习题思路
- 新建一个TextArea(全局变量)，创建一个ScrollPane，传入TextArea
- 创建一个HBox，新建两个Label和两个TextField，以及一个按钮Button，
- 创建一个BorderPane，将ScrollPane设置在中心，把HBox设置在顶部
- 为Button注册一个事件，当按钮按下时检查两个TextField是否为空，不为空则用输入框里的内容为参数传入一个输出到TextArea的方法
- (输出到TextArea的方法)每次调用前清除之前的文本，用TextArea.appendText()方法代替System.out.println()
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代码示例
编程练习题16_13CompareLoans.java
package chapter_16;import java.lang.invoke.StringConcatFactory;import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.Label;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;public class 编程练习题16_13CompareLoans extends Application{private TextArea textArea = new TextArea();@Overridepublic void start(Stage primaryStage) throws Exception {ScrollPane scrollPane = new ScrollPane(textArea);HBox hBox = new HBox(10);TextField tfLoan = new TextField();Label lbLoan = new Label("Loan Amount",tfLoan);lbLoan.setContentDisplay(ContentDisplay.RIGHT);TextField tfYear = new TextField();tfYear.setPrefWidth(30);Label lbYear = new Label("Number of Years",tfYear);lbYear.setContentDisplay(ContentDisplay.RIGHT);Button btShow = new Button("Show Table");hBox.getChildren().addAll(tfLoan,lbLoan, tfYear,lbYear, btShow);BorderPane borderPane = new BorderPane();borderPane.setCenter(scrollPane);borderPane.setTop(hBox);btShow.setOnMouseClicked(e ->{if(!tfLoan.getText().isEmpty()&&!tfYear.getText().isEmpty()) {double loan = Double.valueOf(tfLoan.getText());int year = Integer.valueOf(tfYear.getText());print(loan, year);}});Scene scene = new Scene(borderPane,500, 200);primaryStage.setTitle("编程练习题16_13CompareLoans");primaryStage.setScene(scene);primaryStage.show();}public static void main(String[] args) {Application.launch(args);}public void print(double Loan, int Years) {textArea.clear();double rate = 5.000;textArea.appendText("Interest Rate\t\tMonthly Payment\tTotal Payment\n");while(rate<=8.000) {textArea.appendText(rate+"% ");double monthly_Rate = (rate/1200);double monthly_Pay = (Loan * monthly_Rate )/ (1 - 1/Math.pow(1+monthly_Rate,Years*12));double total_Pay = monthly_Pay * 5 * 12;textArea.appendText("\t\t"+Math.round(monthly_Pay*100.0)/100.0);textArea.appendText("\t\t\t"+Math.round(total_Pay*100.0)/100.0+"\n");rate+=0.125;}}
}
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结果展示
