java代码练习第10课

test042.java

package pack02;


import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;


import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.WindowConstants;


public class test042 extends JFrame
{


public static void main(String[] args)
{
new test042();


  }


public test042()
{
this.setTitle("习题");
this.setLayout(new GridLayout(3,1,5,5));
Container container1 = this.getContentPane();
JTextField textField1 = new JTextField("用户名");
JTextField textField2 = new JTextField();
container1.add(textField1);
container1.add(textField2);


JButton button1 = new JButton("登录");
JButton button2 = new JButton("重置");
JPanel panel1 = new JPanel(new FlowLayout());
panel1.add(button1);
panel1.add(button2);
container1.add(panel1);

button1.addActionListener(new ActionListener()
    {

@Override
public void actionPerformed(ActionEvent e)
{
String text1 = textField1.getText();
String text2= textField2.getText();

if (text1.equals("admin") && text2.equals("xxx"))
        {
JOptionPane.showMessageDialog(null, "登录成功");
        }
else 
        {
JOptionPane.showMessageDialog(null, "登录失败");

        }

      }
    });


this.setSize(500,300);
this.setVisible(true);
this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

  }
}

test043.java

package pack02;


import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;


public class test043
{


public static void main(String[] args)
{
String content[]  = new String[] {"好久不见","最近好吗","常联系"};
File file1 = new File("test.txt");
if (file1.exists())
    {
try
      {
FileWriter writer1 = new FileWriter(file1);
BufferedWriter bufferedWriter1 = new BufferedWriter(writer1);
for (int i = 0; i < content.length; i++)
        {
bufferedWriter1.write(content[i]);
bufferedWriter1.newLine();
        }
bufferedWriter1.close();
writer1.close();
      } catch (Exception e)
      {
e.printStackTrace();
      }
    }
else 
    {
test043.createFile();
    }

try
    {
FileReader reader1 = new FileReader(file1);
BufferedReader bufferedReader1 = new BufferedReader(reader1);
String str1 = null;
int i = 0;
while ((str1 = bufferedReader1.readLine()) != null)
      {
i++;
System.out.println("第" + i + "行：" + str1);
      }
bufferedReader1.close();
reader1.close();
    } catch (Exception e)
    {
e.printStackTrace();
    }


  }

public static void createFile()
{
File file1 = new File("test.txt");
try
    {
file1.createNewFile();
System.out.println("文件已创建");
    } catch (Exception e)
    {
e.printStackTrace();
    }
  }


}

test044.java

package pack02;


import java.awt.event.WindowEvent;
import java.awt.event.WindowFocusListener;


import javax.swing.JFrame;
import javax.swing.WindowConstants;


public class test044 extends JFrame
{
public test044()
{
this.setTitle("窗体事件");
this.addWindowFocusListener(new WindowFocusListener()
    {

@Override
public void windowLostFocus(WindowEvent e)
{
System.out.println("窗口失去了焦点");

      }

@Override
public void windowGainedFocus(WindowEvent e)
{
System.out.println("窗口获得了焦点");

      }
    });
this.setSize(500,500);
this.setVisible(true);
this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
  }


public static void main(String[] args)
{
test044 s1 = new test044();

  }


}

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