java - 理解 Java 中的 KeyEvent 的问题

Question

我目前正在尝试制作一个程序，其中输入三个按钮，每次都会发生不同的情况。

我知道我必须使用keyPressed，但这确实让我感到困惑，因为当我运行程序时，它不会等待我输入任何内容。

由于我对一般编程还很陌生，所以我一直在遵循在线指南，因此如果您有更好的方法来完成所有这些工作，请务必说出来。

import java.awt.event.KeyEvent;

public class Trial {

  public static void main(String[] args) {
    System.out.println("Welcome to the Medical Registration Form program.");
    System.out.println("To enter a new patient's details, press 'N'");
    System.out.println("To access an existing pateient's details, press 'S'");
    System.out.println("To see all patient deatils currently saved, press 'P'");
  }

  public void keyPressed(KeyEvent e) {
    int keyCode = e.getKeyCode();
    if (keyCode == KeyEvent.VK_S) {
      System.out.println("You pressed a valid button");  
    } else {
      System.out.println("You pressed a bad button!");
      e.consume();
    }
  }
}

Answer 1

如果您想使用控制台，请按照以下代码片段操作:

public class Demo{

public static void main(String[] args) {
    // TODO code application logic here

    System.out.println("Welcome to the Medical Registration Form program.");
    System.out.println("To enter a new patient's details, press 'N'");
    System.out.println("To access an existing pateient's details, press 'S'");
    System.out.println("To see all patient deatils currently saved, press 'P'");
    Scanner scan = new Scanner(System.in);
    String input = scan.next();

    if(input.matches("S")){
        System.out.println("You pressed a valid button");  
    } else {
        System.out.println("You pressed a bad button!");

    }
}

否则，从 Jframe 扩展并实现 KeyListener，如下所示:

public class Demo extends JFrame implements KeyListener{

public Demo(){

    this.addKeyListener(this);
}

public static void main(String[] args) {
    // TODO code application logic here

    System.out.println("Welcome to the Medical Registration Form program.");
    System.out.println("To enter a new patient's details, press 'N'");
    System.out.println("To access an existing pateient's details, press 'S'");
    System.out.println("To see all patient deatils currently saved, press 'P'");
    Demo demo = new Demo();
}   

@Override
public void keyPressed(KeyEvent e) {

    int keyCode = e.getKeyCode();
    if(keyCode == KeyEvent.VK_S){
        System.out.println("You pressed a valid button");  
    } else {
        System.out.println("You pressed a bad button!");
        e.consume();
    }
}

@Override
public void keyReleased(KeyEvent e) {
    // TODO Auto-generated method stub

}

@Override
public void keyTyped(KeyEvent e) {
    // TODO Auto-generated method stub

}