格式化
DecimalFormat pre = new DecimalFormat(“”);
JTextField output;
output.setText(pre.format(result));
Applet
题1
import java.applet.*
import java.awt.Graphics;
public class Java_1 extends Applet {
    public void paint(Graphics g){
        g.drawString("欢迎您",25,25);
    }
}
题2
import java.awt.*;
import jave.applet.*;
public class Java_2 extends Applet
{
    TextArea outputArea;
    public void init(){
        setLayout(new BorderLayout());
        outputArea = new TextArea();
        add(outputArea);
        for(long i = 0; i <= 10; i++){
            outputArea.append(i+"!=" +hello(i) +"\n");
        }
    }
}
题3
// 碰到有html的程序，一定是继承JApplet
import java.awt.*;
import javax.swing.*;
public class Java_3 extends JApplet
{
// JApplet的第一个方法是 init
    public void init(){   
    }
}
JOptionPane
题1
import javax.swing.JOptionPane;
// 需要记住的代码
JOptionPane.showMessageDialog(null, output, "",...)
其他的有: showConfirmDialog(), showInputDialog(), showOptionDialog()
JOptionPane.showMessageDialog(null, output, "字符串",
JOptionPane.INFORMATION_MESSAGE);
题2
// 输入框
String input = JOptionPane.showInputDialog("输入一个整数");
Container c = getContentPane()
JFrame相关
题1
import javax.swing.*;
public SimpleThread(String str) {
    super(str);
}
题2
import javax.swing.*;
class BeijingPanel extends JPanel
{
    public BeijingPanel(){
        setLayout(new BorderLayout());
    }
}
frame.getContentPane().add();
题3
import java.swing.JFrame;
str.length();
str.charAt(3);
// 使窗口隐藏
frame.dispose();    //使窗口隐藏或消除
题4
JMenu m1 = new JMenu("Edit");
SelectedFile().getPath()
JButton calcBtn = new JButton("计算");
题5
public class Java_3 implements ActionListener
{
    JFileChooser fc = new JFileChooser();
    int selected = fc.showOpenDialog();
    File myFile = fc.showOpenDialog();
    myFile.getName()
}
题6
JFrame f = new JFrame();
Container contentPane = f.getContentPane();
JTable table = new JTable();
table.addMouseListener(new MouseApapter());
计算机专业java
题7
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT)
题8
JTextArea result = new JTextArea();
result.append(str)
Listener
题1
public class Java_3 extends MouseAdapter implements ActionListener{}
class MouseMotion extends MouseMotionAdapter{}
题2
class A implements ActionListener
{
    public void actionPerformed(ActionEvent event)
}
题3
int n = und(21*x)
input.addActionListener(this);
输入输出流
题1
ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(new File()))
oos.writeObject(new User())
ObjectInputStream ooi = new ObjectInputStream(new FileInputStream(new File()))
ooi.readObject()
import java.io.Serializable
题2
FileWriter out = new FileWriter(new File(""));
FileReader in = new FileReader(new File(""));
class ImagePanel extends JPanel
题3
DataOutputStream out = new DataOutputStream(new FileOutputStream(""));
out.writeChar(aa[i]);
题4
import java.awt.*;
FileWriter out = new FileWriter("");
out.write(str);
解题思想
题1
2008 -> 8002
int a,x = 2008;
while(x!=0){
    a = x % 10;
    x = x / 10;
}
题2
矩阵乘法
public class Java_2 {
    public static void main(String args[]) {
        int [][]a = {{2, 3, 4}, {4, 6, 5}};
        int [][]b = {{1, 5, 2, 8}, {5, 9, 10, -3}, {2, 7, -5, -18}};
        //*********Found**********
        int [][]c = new int[2][4];
        for (int i = 0; i < 2; i++) {
            //*********Found**********
            for (int j = 0; j <4; j++) {
                //*********Found**********
                c[i][j] = 0;
                for (int k = 0; k < 3; k++)
                    //*********Found**********
                    c[i][j] += a[i][k] * b[k][j];
                System.out.print(c[i][j] + "  ");
            }
            System.out.println();
        }
    }
}
题3
import java.io.*;
public class Java_1
{
    public static void main(String[] args) throws Exception{
        InputStreamReader ir = new InputSteamReader(System.in);
        BufferedReader in = new BufferedReader(ir);
        String s = in.readLine();
        int year = Integer.parseInt(s);
        if(year%4==0 && year%100!=0 || year%400==0){
            System.out.println(year+"是闰年");
        }else{
            System.out.println(year+"不是闰年")
        }
    }
}
题4
自定义排序
public class Java_2
{ 
  public static void main(String[] args)
  {
      Student[] java = new Student[3];
      java[0] = new Student("李明", 80);
      java[1] = new Student("赵冬", 75);
      java[2] = new Student("王晓", 98);
      //*********Found**********
      Arrays.sort(java);

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