java代碼點

⑴ java中的.（點）的用法，有誰知道嗎

System.out.println(f.a); // 為什麼不是輸出f.a++？

表示輸出f這個對象中的a變數的值
如果你想輸出f.a++
應該這樣
System.out.println("f.a++");

⑵ Java100行以上源代碼，至少五個class以及一個interface，可以簡單點

下面是一個可能的Java源代碼，它包含了一個介面租沖薯（Shape）和五個類（Circle, Rectangle, Triangle, Square 和 Main）。它的功能是計算不同形狀的面積和周長。
//定義一個介面Shape，有兩判指個抽象方法：getArea()和getPerimeter()interface Shape { double getArea(); double getPerimeter();
}//定義一個類Circle，實現Shape介面class Circle implements Shape { //定義一個私有屬性radius，表示圓的半徑
private double radius; //定義一個公有構造方法，用於初始化radius
public Circle(double radius) { this.radius = radius;
} //實現getArea()方法，返回圓的面積
public double getArea() { return Math.PI * radius * radius;
} //實現getPerimeter()方法，返回圓的周長
public double getPerimeter() { return Math.PI * radius * 2;
}
}//定義一個類Rectangle，實現Shape介面class Rectangle implements Shape { //定義兩個私有屬性width和height，表示矩形的寬度和高度
private double width; private double height; //定義一個公有構造方法，用於初始化width和height
public Rectangle(double width, double height) { this.width = width; this.height = height;
} //實現getArea()方法，返回矩形的面積
public double getArea() { return width * height;
} //實現getPerimeter()方法，返回矩形的周長
public double getPerimeter() { return (width + height) *2;
}
}//定義一個類Triangle，實現Shape介面class Triangle implements Shape { //定義三個私有屬性a,b,c表示三角形的三條邊長
private double a; private double b; private double c; //定義一個公有構造方法，用於初始化a,b,c，並檢查是否滿足三角形條件（任意兩邊之和大於第三邊）
public Triangle(double a, double b, double c) throws Exception{ if (a + b > c && a + c > b && b + c > a) {
this.a = a; this.b = b;
this.c = c;
} else {
throw new Exception("Invalid triangle");
}
} //實現getArea()方法，返回三角形的面積（使用海倫公式）
public double getArea() { //計算半周長p
double p = (a + b + c) /2; //計算並返回面積s（使用Math.sqrt()函數求平方根）
return Math.sqrt(p * (p - a) * (p - b) * (p - c));
} //實現getPerimeter()方法，返回三角形的周長
public double getPerimeter(){ return a + b + c;
}
}//定義一個類Square，繼承Rectangle類，並重寫構造方法和toString()方法class Square extends Rectangle { //重寫構造方法，在調用父類構造方法時傳入相弊者同的參數side作為width和height
public Square(double side){ super(side, side);
} //重寫toString()方法，在原來基礎上加上"Square:"前綴，並只顯示side屬性而不顯示width和height屬性（使用String.format()函數格式化字元串）
@Override
public String toString(){ return String.format("Square: side=%.2f", super.width); /* 或者直接使用super.getPerimeter()/4作為side */
/* return String.format("Square: side=%.2f", super.getPerimeter()/4); */

/* 注意：不能直接訪問super.side屬性，

⑶ 求 JAVA 算24點的代碼

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class calculate24 extends JFrame{

private javax.swing.JPanel jContentPane = null;
private JLabel jLabel = null;
private JLabel jLabel1 = null;
private JTextField jTextField = null;
private JTextField jTextField1 = null;
private JTextArea jTextArea = null;
private JLabel jLabel2 = null;
private JButton jButton = null;
private JScrollPane jScrollPane = null;

private JButton jButton1 = null;
private JButton jButton2 = null;
private JButton jButton3 = null;
private JButton jButton4 = null;
private JButton jButton5 = null;
private JButton jButton6 = null;
private JButton jButton7 = null;
private JButton jButton8 = null;
private JButton jButton9 = null;
private JButton jButton10 = null;
/**
* This is the default constructor
*/
public calculate24() {
super();
initialize();
}

/**
* This method initializes this
*
* @return void
*/
private void initialize() {
this.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
this.setBounds(200, 200, 565, 452);
this.setContentPane(getJContentPane());
this.setTitle("24點");
}

/**
* This method initializes jContentPane
*
* @return javax.swing.JPanel
*/
private javax.swing.JPanel getJContentPane() {
if (jContentPane == null) {
jLabel2 = new JLabel();
jLabel1 = new JLabel();
jLabel = new JLabel();
jContentPane = new javax.swing.JPanel();
jContentPane.setLayout(null);
jLabel.setBounds(66, 52, 150, 45);
jLabel.setText("please unter four number");
jLabel1.setBounds(253, 52, 282, 45);
jLabel1.setText("please unter how many result do you want to get");
jLabel2.setBounds(354, 201, 70, 36);
jLabel2.setText("result");
jContentPane.add(getJButton(), null);
jContentPane.add(jLabel, null);
jContentPane.add(jLabel1, null);
jContentPane.add(getJTextField(), null);
jContentPane.add(getJTextField1(), null);
jContentPane.add(jLabel2, null);
jContentPane.add(getJScrollPane(), null);
jContentPane.add(getJButton1(), null);
jContentPane.add(getJButton2(), null);
jContentPane.add(getJButton3(), null);
jContentPane.add(getJButton4(), null);
jContentPane.add(getJButton5(), null);
jContentPane.add(getJButton6(), null);
jContentPane.add(getJButton7(), null);
jContentPane.add(getJButton8(), null);
jContentPane.add(getJButton9(), null);
jContentPane.add(getJButton10(), null);
}
return jContentPane;
}

/**
* This method initializes jTextField
*
* @return javax.swing.JTextField
*/
private JTextField getJTextField() {
if (jTextField == null) {
jTextField = new JTextField();
jTextField.setBounds(67, 84, 149, 41);
jTextField.addFocusListener(new java.awt.event.FocusAdapter() {
public void focusGained(java.awt.event.FocusEvent e) {
jTextField.select(0,jTextField.getText().length());
}
});
}
return jTextField;
}

/**
* This method initializes jTextField1
*
* @return javax.swing.JTextField
*/
private JTextField getJTextField1() {
if (jTextField1 == null) {
jTextField1 = new JTextField();
jTextField1.setBounds(293, 81, 161, 41);
jTextField1.setNextFocusableComponent(jButton);
}
return jTextField1;
}

/**
* This method initializes jTextArea
*
* @return javax.swing.JTextArea
*/
private JTextArea getJTextArea() {
if (jTextArea == null) {
jTextArea = new JTextArea();
jTextArea.setTabSize(8);
}
return jTextArea;
}

public static String bbb(List list1, List list2) {
float result = 0;
for (int i = list1.size(); i > 0; i-- ) {
if (list1.contains("*")) {
int j = list1.indexOf("*");
result = Float.parseFloat((String)list2.get(j))
* Float.parseFloat((String)list2.get(j + 1));
list1.remove(j);
list2.remove(j);
list2.remove(j);
list2.add(j, String.valueOf(result));
} else if (list1.contains("/")) {
int j = list1.indexOf("/");
result = Float.parseFloat((String)list2.get(j))
/ Float.parseFloat((String)list2.get(j + 1));
list1.remove(j);
list2.remove(j);
list2.remove(j);
list2.add(j, String.valueOf(result));
} else if (list1.contains("+")) {
int j = list1.indexOf("+");
result = Float.parseFloat((String)list2.get(j))
+ Float.parseFloat((String)list2.get(j + 1));
list1.remove(j);
list2.remove(j);
list2.remove(j);
list2.add(j, String.valueOf(result));
} else if (list1.contains("-")) {
int j = list1.indexOf("-");
result = Float.parseFloat((String)list2.get(j))
- Float.parseFloat((String)list2.get(j + 1));
list1.remove(j);
list2.remove(j);
list2.remove(j);
list2.add(j, String.valueOf(result));
}
}
return (String)list2.get(0);
}

private static void bbb(String str, String sPrint, List list) {
if (!"".equals(str.trim()) ? false : list.add(sPrint))
;
for (int i = 0; i < str.length() && ( !"".equals(str.trim()) ); i++ )
if (str.charAt(i) != ' ')
bbb(str.replace(str.charAt(i), ' '), sPrint + str.charAt(i),
list);
}

private static List bbb(String str, List list) {
List result = new ArrayList();
String a1 = str.substring(0, 1);
String b1 = str.substring(1, 2);
String c1 = str.substring(2, 3);
String d1 = str.substring(3, 4);
String[] a11 = new String[] { a1, b1, c1, d1 };
for (int i = 0; i < list.size(); i++ ) {
String temp = (String)list.get(i);
int a = Integer.parseInt(temp.substring(0, 1));
int b = Integer.parseInt(temp.substring(1, 2));
int c = Integer.parseInt(temp.substring(2, 3));
int d = Integer.parseInt(temp.substring(3, 4));
String tempStr = a11[a] + a11[b] + a11[c] + a11[d];
if(!result.contains(tempStr)){
result.add(tempStr);
}

}
return result;
}

public List test(String param, int x) {
int y = 0;
List result = new ArrayList();
List a11 = new ArrayList();
calculate24.bbb("0123", "", a11);
List a1 = calculate24.bbb(param, a11);
for (int m = 0; m < a1.size(); m++ ) {
String param1 = (String)a1.get(m);
int[] a = new int[] { Integer.parseInt(param1.substring(0, 1)),
Integer.parseInt(param1.substring(1, 2)),
Integer.parseInt(param1.substring(2, 3)),
Integer.parseInt(param1.substring(3, 4)) };
String[] e = new String[] { "*", "/", "+", "-" };
for (int i = 0; i < 4; i++ ) {
for (int j = 0; j < 4; j++ ) {
for (int k = 0; k < 4; k++ ) {
List aa = new ArrayList();
aa.add(String.valueOf(a[0]));
aa.add(String.valueOf(a[1]));
aa.add(String.valueOf(a[2]));
aa.add(String.valueOf(a[3]));
List bb = new ArrayList();
bb.add(e[i]);
bb.add(e[j]);
bb.add(e[k]);
String s = a[0] + e[i] + a[1] + e[j] + a[2] + e[k]
+ a[3];
String tempS = s;
s = calculate24.bbb(bb, aa);
if (Float.parseFloat(s) == 24) {
y++ ;
result.add(tempS + "=24");
if (y == x) {
return result;
}
}

List temp1 = new ArrayList();
List temp2 = new ArrayList();
temp1.add(String.valueOf(a[0]));
temp1.add(String.valueOf(a[1]));
temp2.add(e[i]);
String temp = calculate24.bbb(temp2, temp1);
aa.clear();
aa.add(temp);
aa.add(String.valueOf(a[2]));
aa.add(String.valueOf(a[3]));
bb.clear();
bb.add(e[j]);
bb.add(e[k]);
s = "(" + a[0] + e[i] + a[1] + ")" + e[j] + a[2] + e[k]
+ a[3];
tempS = s;
s = calculate24.bbb(bb, aa);
if (Float.parseFloat(s) == 24) {
y++ ;
result.add(tempS + "=24");
if (y == x) {
return result;
}
}

temp1.clear();
temp2.clear();
temp1.add(String.valueOf(a[1]));
temp1.add(String.valueOf(a[2]));
temp2.add(e[j]);
temp = calculate24.bbb(temp2, temp1);
aa.clear();
aa.add(String.valueOf(a[0]));
aa.add(temp);
aa.add(String.valueOf(a[3]));
bb.clear();
bb.add(e[i]);
bb.add(e[k]);
s = a[0] + e[i] + "(" + a[1] + e[j] + a[2] + ")" + e[k]
+ a[3];
tempS = s;
s = calculate24.bbb(bb, aa);
if (Float.parseFloat(s) == 24) {
y++ ;
result.add(tempS + "=24");
if (y == x) {
return result;
}
}

temp1.clear();
temp2.clear();
temp1.add(String.valueOf(a[2]));
temp1.add(String.valueOf(a[3]));
temp2.add(e[k]);
temp = calculate24.bbb(temp2, temp1);
aa.clear();
aa.add(String.valueOf(a[0]));
aa.add(String.valueOf(a[1]));
aa.add(temp);
bb.clear();
bb.add(e[i]);
bb.add(e[j]);
s = a[0] + e[i] + a[1] + e[j] + "(" + a[2] + e[k]
+ a[3] + ")";
tempS = s;
s = calculate24.bbb(bb, aa);
if (Float.parseFloat(s) == 24) {
y++ ;
result.add(tempS + "=24");
if (y == x) {
return result;
}
}

temp1.clear();
temp2.clear();
temp1.add(String.valueOf(a[0]));
temp1.add(String.valueOf(a[1]));
temp1.add(String.valueOf(a[2]));
temp2.add(e[i]);
temp2.add(e[j]);
temp = calculate24.bbb(temp2, temp1);
aa.clear();
aa.add(temp);
aa.add(String.valueOf(a[3]));
bb.clear();
bb.add(e[k]);
s = "(" + a[0] + e[i] + a[1] + e[j] + a[2] + ")" + e[k]
+ a[3];
tempS = s;
s = calculate24.bbb(bb, aa);
if (Float.parseFloat(s) == 24) {
y++ ;
result.add(tempS + "=24");
if (y == x) {
return result;
}
}

temp1.clear();
temp2.clear();
temp1.add(String.valueOf(a[1]));
temp1.add(String.valueOf(a[2]));
temp1.add(String.valueOf(a[3]));
temp2.add(e[j]);
temp2.add(e[k]);
temp = calculate24.bbb(temp2, temp1);
aa.clear();
aa.add(String.valueOf(a[0]));
aa.add(temp);
bb.clear();
bb.add(e[i]);
s = a[0] + e[i] + "(" + a[1] + e[j] + a[2] + e[k]
+ a[3] + ")";
tempS = s;
s = calculate24.bbb(bb, aa);
if (Float.parseFloat(s) == 24) {
y++ ;
result.add(tempS + "=24");
if (y == x) {
return result;
}
}

temp1.clear();
temp2.clear();
temp1.add(String.valueOf(a[0]));
temp1.add(String.valueOf(a[1]));
temp2.add(e[i]);
temp = calculate24.bbb(temp2, temp1);

List temp3 = new ArrayList();
List temp4 = new ArrayList();
temp3.add(String.valueOf(a[2]));
temp3.add(String.valueOf(a[3]));
temp4.add(e[k]);
String temp11 = calculate24.bbb(temp4, temp3);
aa.clear();
aa.add(temp);
aa.add(temp11);
bb.clear();
bb.add(e[j]);
s = "(" + a[0] + e[i] + a[1] + ")" + e[j] + "(" + a[2]
+ e[k] + a[3] + ")";
tempS = s;
s = calculate24.bbb(bb, aa);
if (Float.parseFloat(s) == 24) {
y++ ;
result.add(tempS + "=24");
if (y == x) {
return result;
}
}
}
}
}
}
return result;
}

public static boolean check(String param1) {
Pattern pattern = Pattern.compile("[0-9]{4}");
Matcher matcher = pattern.matcher((CharSequence)param1);
boolean result = matcher.matches();
if (result == false) {
JOptionPane.showMessageDialog(null, "please enter correct number");
return false;
} else {
return true;
}

}

public static boolean check1(String param2) {
if(param2 == null){
JOptionPane.showMessageDialog(null, "please enter correct number");
return false;
}
Pattern pattern = Pattern.compile("[0-9]{0,99}");
Matcher matcher = pattern.matcher((CharSequence)param2);
boolean result = matcher.matches();
if (result == false) {
JOptionPane.showMessageDialog(null, "please enter correct number");
return false;
} else {
return true;
}

}

/**
* This method initializes jButton
*
* @return javax.swing.JButton
*/
private JButton getJButton() {
if (jButton == null) {
jButton = new JButton();
jButton.setBounds(81, 275, 110, 54);
jButton.setText("calculate");
jButton.addKeyListener(new java.awt.event.KeyAdapter() {
public void keyPressed(java.awt.event.KeyEvent e) {
if(e.getKeyCode()==10){
if (check(jTextField.getText())
&& check1(jTextField1.getText())) {
if(!jTextField1.getText().equals("0")){
List b = test(jTextField.getText(), Integer
.parseInt(jTextField1.getText()));
String temp = "";
for (int i = 0; i < b.size(); i++ ) {
temp = temp + b.get(i) + "\n";
}
if (b.size() == 0) {
jTextArea.setText("NO RESULT");
} else {
jTextArea.setText(temp);
}
}else{
JOptionPane.showMessageDialog(null, "please enter correct number");
}
}
}
}
});
jButton.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {

if (check(jTextField.getText())
&& check1(jTextField1.getText())) {
if(!jTextField1.getText().equals("0")){
List b = test(jTextField.getText(), Integer
.parseInt(jTextField1.getText()));
String temp = "";
for (int i = 0; i < b.size(); i++ ) {
temp = temp + b.get(i) + "\n";
}
if (b.size() == 0) {
jTextArea.setText("NO RESULT");
} else {
jTextArea.setText(temp);
}
}else{
JOptionPane.showMessageDialog(null, "please enter correct number");
}
}

}
});
}
return jButton;
}

/**
* This method initializes jScrollPane
*
* @return javax.swing.JScrollPane
*/
private JScrollPane getJScrollPane() {
if (jScrollPane == null) {
jScrollPane = new JScrollPane();
jScrollPane.setBounds(267, 238, 216, 124);
jScrollPane.setViewportView(getJTextArea());
}
return jScrollPane;
}

/**
* This method initializes jButton1
*
* @return javax.swing.JButton
*/
private JButton getJButton1() {
if (jButton1 == null) {
jButton1 = new JButton();
jButton1.setBounds(40, 148, 42, 28);
jButton1.setText("1");
jButton1.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
jTextField.setText(jTextField.getText()+"1");
}
});
}
return jButton1;
}
/**
* This method initializes jButton2
*
* @return javax.swing.JButton
*/
private JButton getJButton2() {
if (jButton2 == null) {
jButton2 = new JButton();
jButton2.setBounds(90, 148, 42, 28);
jButton2.setText("2");
jButton2.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
jTextField.setText(jTextField.getText()+"2");
}
});
}
return jButton2;
}
/**
* This method initializes jButton3
*
* @return javax.swing.JButton
*/
private JButton getJButton3() {
if (jButton3 == null) {
jButton3 = new JButton();
jButton3.setBounds(140, 148, 42, 28);
jButton3.setText("3");
jButton3.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
jTextField.setText(jTextField.getText()+"3");
}
});
}
return jButton3;
}
/**
* This method initializes jButton4
*
* @return javax.swing.JButton
*/
private JButton getJButton4() {
if (jButton4 == null) {
jButton4 = new JButton();
jButton4.setBounds(190, 148, 42, 28);
jButton4.setText("4");
jButton4.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
jTextField.setText(jTextField.getText()+"4");
}
});
}
return jButton4;
}
/**
* This method initializes jButton5
*
* @return javax.swing.JButton
*/
private JButton getJButton5() {
if (jButton5 == null) {
jButton5 = new JButton();
jButton5.setBounds(240, 148, 42, 28);
jButton5.setText("5");
jButton5.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
jTextField.setText(jTextField.getText()+"5");
}
});
}
return jButton5;
}
/**
* This method initializes jButton6
*
* @return javax.swing.JButton
*/
private JButton getJButton6() {
if (jButton6 == null) {
jButton6 = new JButton();
jButton6.setBounds(40, 188, 42, 28);
jButton6.setText("6");
jButton6.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
jTextField.setText(jTextField.getText()+"6");
}
});
}
return jButton6;
}
/**
* This method initializes jButton7
*
* @return javax.swing.JButton
*/
private JButton getJButton7() {
if (jButton7 == null) {
jButton7 = new JButton();
jButton7.setBounds(90, 188, 42, 28);
jButton7.setText("7");
jButton7.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
jTextField.setText(jTextField.getText()+"7");
}
});
}
return jButton7;
}
/**
* This method initializes jButton8
*
* @return javax.swing.JButton
*/
private JButton getJButton8() {
if (jButton8 == null) {
jButton8 = new JButton();
jButton8.setBounds(140, 188, 42, 28);
jButton8.setText("8");
jButton8.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
jTextField.setText(jTextField.getText()+"8");
}
});
}
return jButton8;
}
/**
* This method initializes jButton9
*
* @return javax.swing.JButton
*/
private JButton getJButton9() {
if (jButton9 == null) {
jButton9 = new JButton();
jButton9.setBounds(190, 188, 42, 28);
jButton9.setText("9");
jButton9.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
jTextField.setText(jTextField.getText()+"9");
}
});
}
return jButton9;
}
/**
* This method initializes jButton10
*
* @return javax.swing.JButton
*/
private JButton getJButton10() {
if (jButton10 == null) {
jButton10 = new JButton();
jButton10.setBounds(240, 188, 42, 28);
jButton10.setText("0");
jButton10.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent e) {
jTextField.setText(jTextField.getText()+"0");
}
});
}
return jButton10;
}
/**
* Launches this application
*/
public static void main(String[] args) {
calculate24 application = new calculate24();
application.show();

}
} // @jve:decl-index=0:visual-constraint="10,10"