问题描述
- Java图形界面 简易BMI计算器怎样设计算法
-
老师出差去了 布置作业做一个简易BMI计算器
写了半天才写出一个图形界面
不知道怎样实现键盘录入身高、体重，点击评估按钮得到BMI和结果（结果输出的是胖，瘦，正常三种情况）
代码、界面如下:
解决方案
你的核心问题是如何对按钮进行响应，需要看下ActionListener的相关方法。
public class BMI extends JFrame{
private JLabel lblHeight;
private JLabel lblWeight;
private JLabel lblBMI;
private JLabel lblResult;
private JButton btnRun;
private JPanel pnlMain;
private JTextField txtHeight;
private JTextField txtWeight;
private JTextField txtBMI;
private JTextField txtResult;
DecimalFormat dformat = new DecimalFormat("#.00");
public BMI(){
lblHeight = new JLabel("身高(米/m)");
txtHeight = new JTextField(10);
lblWeight = new JLabel("体重(千克/kg)");
txtWeight = new JTextField(10);
lblBMI = new JLabel("健康值(BMI)");
txtBMI = new JTextField(10);
lblResult = new JLabel("结果");
txtResult = new JTextField(10);
btnRun = new JButton("评估");
pnlMain = new JPanel();
pnlMain.setLayout(null);
lblHeight.setBounds(100, 50, 80, 25);
txtHeight.setBounds(200, 50, 100, 25);
lblWeight.setBounds(100, 80, 80, 25);
txtWeight.setBounds(200, 80, 100, 25);
lblBMI.setBounds(100, 110, 80, 25);
txtBMI.setBounds(200, 110, 100, 25);
lblResult.setBounds(100, 170, 80, 25);
txtResult.setBounds(200, 170, 100, 25);
btnRun.setBounds(150, 140, 80, 25);
pnlMain.add(lblHeight);
pnlMain.add(txtHeight);
pnlMain.add(lblWeight);
pnlMain.add(txtWeight);
pnlMain.add(lblBMI);
pnlMain.add(txtBMI);
pnlMain.add(lblResult);
pnlMain.add(txtResult);
pnlMain.add(btnRun);
this.setContentPane(pnlMain);
setSize(400,300);
setTitle("健康评估");
setVisible(true);
setResizable(false);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
btnRun.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if( txtWeight.getText() == null){
JOptionPane.showMessageDialog(null, "身高为空，请输入一个正值身高！");
return;
}
if( txtHeight.getText() == null){
JOptionPane.showMessageDialog(null, "体重为空，请输入一个正值体重！");
return;
}
double weight = Double.valueOf(txtWeight.getText());
if(weight <= 0 ){
JOptionPane.showMessageDialog(null, "体重为0，请输入一个正值体重。");
return;
}
double height = Double.valueOf(txtHeight.getText());
if(height <= 0 ){
JOptionPane.showMessageDialog(null, "身高为0，请输入一个正值身高。");
return;
}
double bmi = weight/height/height;
txtBMI.setText(dformat.format(bmi));
txtResult.setText(getResult(bmi));
}
});
}
private String getResult(double bmi) {
// TODO Auto-generated method stub
if(bmi < 18.5){
return "瘦";
}else if(bmi>=18.5 && bmi < 24){
return "正常";
}else{
return "胖";
}
}
public static void main(String[] args) {
new BMI();
}
}
解决方案二：
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class BMI extends JFrame {
/**
* 简易BMI计算机
*/
private static final long serialVersionUID = -2317974201224415240L;
private JLabel lblHeight;
private JLabel lblWeight;
private JLabel lblBMI;
private JLabel lblResult;
private JButton btnRun;
private JPanel pnlMain;
private JTextField txtHeight;
private JTextField txtWeight;
private JTextField txtBMI;
private JTextField txtResult;
DecimalFormat dformat = new DecimalFormat("#.00");
public BMI() {
lblHeight = new JLabel("身高(米/m)");
txtHeight = new JTextField(10);
lblWeight = new JLabel("体重(千克/kg)");
txtWeight = new JTextField(10);
lblBMI = new JLabel("健康值(BMI)");
txtBMI = new JTextField(10);
lblResult = new JLabel("结果");
txtResult = new JTextField(10);
btnRun = new JButton("评估");
pnlMain = new JPanel();
pnlMain.setLayout(null);
lblHeight.setBounds(100, 50, 80, 25);
txtHeight.setBounds(200, 50, 100, 25);
lblWeight.setBounds(100, 80, 80, 25);
txtWeight.setBounds(200, 80, 100, 25);
lblBMI.setBounds(100, 110, 80, 25);
txtBMI.setBounds(200, 110, 100, 25);
lblResult.setBounds(100, 170, 80, 25);
txtResult.setBounds(200, 170, 100, 25);
btnRun.setBounds(150, 140, 80, 25);
pnlMain.add(lblHeight);
pnlMain.add(txtHeight);
pnlMain.add(lblWeight);
pnlMain.add(txtWeight);
pnlMain.add(lblBMI);
pnlMain.add(txtBMI);
pnlMain.add(lblResult);
pnlMain.add(txtResult);
pnlMain.add(btnRun);
this.setContentPane(pnlMain);
setSize(400, 300);
setTitle("健康评估");
setVisible(true);
setResizable(false);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
btnRun.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if ("".equals(txtHeight.getText())) {
JOptionPane.showMessageDialog(null, "身高为空，请输入一个正值身高！");
return;
}
if ("".equals(txtWeight.getText())) {
JOptionPane.showMessageDialog(null, "体重为空，请输入一个正值体重！");
return;
}
double height = Double.valueOf(txtHeight.getText());
if (height <= 0) {
JOptionPane.showMessageDialog(null, "身高低于o.1cm，请输入一个正值身高。");
return;
}
double weight = Double.valueOf(txtWeight.getText());
if (weight <= 0) {
JOptionPane.showMessageDialog(null, "体重小于0.1kg，请输入一个正值体重。");
return;
}
// BMl＝[体重(千克)／身高(米)]/2
double bmi = weight / height / 2;
txtBMI.setText(dformat.format(bmi));
txtResult.setText(getResult(bmi));
}
});
}
private String getResult(double bmi) {
// BMl＜18.5为消瘦；BMl 在18.5～24.9之间为正常；BMl≥25为超重；
if (bmi < 18.5) {
return "瘦";
} else if (bmi >= 18.5 && bmi < 25) {
return "正常";
} else {
return "胖";
}
}
public static void main(String[] args) {
new BMI();
}
}
百度了一下BMI的计算公式，好像有几种，不过都差异不大，楼主问的算法应该不是问题了，
引用二楼的回答，判断输入是否空值，用null会出异常，所以我改成了"".equals()，应该差不多了。
解决方案三：
同问，有知道的吗？谢了！
时间： 2024-09-17 04:16:53