Question

JAVA题目

1、 编写一个小应用程序，小应用程序窗口中有一个按钮，点击这个按钮时，点击按钮的次数会显示在按钮上。
2、 设计一个窗口，窗口中有一个文本框。程序对键盘输入进行监视，当输入一个整数和回车符时，在文本框输出1至该整数的数列和；如果中间输入非数字的其他字符，在本文框中显示“输入错误，重新输入”的字样。
（用JAVA）

Answer 1

1.
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;

public class Count extends JFrame {

private static final long serialVersionUID = 1L;

public static void main(String args[]) {
try {
Count frame = new Count();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}

public Count() {
super();
setTitle("Count");
setBounds(100, 100, 200, 200);
getContentPane().setLayout(null);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

final JButton btn = new JButton();
btn.setText("0");
btn.addActionListener(new ActionListener() {
int i = 1;
public void actionPerformed(ActionEvent arg0) {
btn.setText(String.valueOf(i));
i++;
}
});
btn.setBounds(50, 71, 99, 23);
getContentPane().add(btn);
}
}

---------------------
2.
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

import javax.swing.JFrame;
import javax.swing.JTextField;

public class Input extends JFrame {

private static final long serialVersionUID = 1L;

private JTextField txt;

public static void main(String args[]) {
try {
Input frame = new Input();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}

public Input() {
super();
setTitle("Input");
setResizable(false);
getContentPane().setLayout(null);
setBounds(100, 100, 200, 200);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

txt = new JTextField();
txt.setBounds(48, 61, 90, 21);
getContentPane().add(txt);
txt.addKeyListener(new KeyAdapter(){
public void keyPressed(KeyEvent e){
if(e.getKeyCode()==KeyEvent.VK_ENTER){
if(txt.getText().matches("\\d+")){
int sum = 0;
int end = Integer.parseInt(txt.getText());
for(int i = 1;i<=end;i++){
sum = sum + i;
}
txt.setText(String.valueOf(sum));
}else{
txt.setText("输入错误，重新输入");
}
}else{
return;
}
}
});
}
}

Answer 2

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;

public class Count extends JFrame {

private static final long serialVersionUID = 1L;

public static void main(String args[]) {
try {
Count frame = new Count();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}

public Count() {
super();
setTitle("Count");
setBounds(100, 100, 200, 200);
getContentPane().setLayout(null);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

final JButton btn = new JButton();
btn.setText("0");
btn.addActionListener(new ActionListener() {
int i = 1;
public void actionPerformed(ActionEvent arg0) {
btn.setText(String.valueOf(i));
i++;
}
});
btn.setBounds(50, 71, 99, 23);
getContentPane().add(btn);
}
}