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mport java.util.*;
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public class HuiWen
{
public static void main(String[] args)
{
Scanner in=new Scanner(System.in);
System.out.println("please input a String:");
String st=in.nextLine();
String s=st.toLowerCase();
int i=0;
int j=s.length()-1;
boolean t=true;
char first=s.charAt(i);
char last=s.charAt(j);
for(;ij;)
{
while(!(first='a'first='z'))
{
i++;
first=s.charAt(i);
}
while(!(last='a'last='z'))
{
j--;
last=s.charAt(i);
}
if(i=j)
break;
if(first==last)
{
i++;
j--;
first=s.charAt(i);
last=s.charAt(j);
}
else
{
t=false;
break;
}
}
if(t)
System.out.println(st+"是回文串");
else
System.out.println(st+"不是回文串");
}
}
//判断是否为回文字串
//什么实用的程序，说具体点！你要计算器的程序吗？
//下面是计算器的程序，把分拿来吧！
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Calculator
{
public static void main(String[] args)
{
CalculatorFrame frame=new CalculatorFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
class CalculatorFrame extends JFrame
{
public CalculatorFrame()
{
setTitle("Calculator");
CalculatorPanel panel=new CalculatorPanel();
add(panel);
pack();
}
}
class CalculatorPanel extends Panel
{
public CalculatorPanel()
{
setLayout(new BorderLayout());
result=0;
lastCommand="=";
start=true;
flag=true;
display=new JButton("0");
display.setEnabled(false);
add(display,BorderLayout.NORTH);
ActionListener insert=new InsertAction();
ActionListener command=new CommandAction();
panel=new JPanel();
panel.setLayout(new GridLayout(4,5));
addButton("7",insert);
addButton("8",insert);
addButton("9",insert);
addButton("/",command);
addButton("CE",command);
addButton("4",insert);
addButton("5",insert);
addButton("6",insert);
addButton("*",command);
addButton("Backspace",command);
addButton("1",insert);
addButton("2",insert);
addButton("3",insert);
addButton("-",command);
addButton("sqrt",command);
addButton("0",insert);
addButton(".",insert);
addButton("=",command);
addButton("+",command);
addButton("1/x",command);
add(panel,BorderLayout.CENTER);
}
private void addButton(String label,ActionListener listener)
{
JButton button=new JButton(label);
button.addActionListener(listener);
panel.add(button);
}
private class InsertAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String input=event.getActionCommand();
if(startflag)
{
display.setText("");
start=false;
}
if(flag)
display.setText(display.getText()+input);
}
}
private class CommandAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String command=event.getActionCommand();
if(command.equals("CE"))
{
display.setText("0");
start=true;
flag=true;
command="=";
}
else
if(startflag)
{
if(command.equals("-"))
{
display.setText(command);
start=false;
}
else
if((command.equals("1/x")||command.equals("sqrt"))flag)
calculate(Double.parseDouble(display.getText()),command);
else
if(flag)
lastCommand=command;
}
else
{
if(command.equals("Backspace")flag)
{
String s=display.getText();
char[] s1=s.toCharArray();
if(s.length()=2)
{
String s2=new String(s1,0,s.length()-1);
display.setText(s2);
}
else
{
display.setText("0");
start=true;
}
}
else if(flag)
{
calculate(Double.parseDouble(display.getText()),command);
lastCommand=command;
start=true;
}
}
}
}
public void calculate(double x,String command)
{
if(lastCommand.equals("+")) result+=x;
else if(lastCommand.equals("-")) result-=x;
else if(lastCommand.equals("/"))
{
if(x!=0)
result/=x;
else
{
display.setText("除数不能为0");
start=false;
flag=false;
return;
}
}
else if(lastCommand.equals("*")) result*=x;
else if(command.equals("1/x"))
{
if(x!=0)
result=1/x;
else
{
display.setText("除数不能为0");
start=false;
flag=false;
return;
}
}
else if(command.equals("sqrt"))
{
if(x=0)
result=Math.sqrt(x);
else
{
display.setText("函数输入无效");
start=false;
flag=false;
return;
}
}
else if(lastCommand.equals("=")) result=x;
display.setText(""+result);
}
private JButton display;
private JPanel panel;
private double result;
private String lastCommand;
private boolean start;
private boolean flag;
}
//都是从新手过来的，以下代码供参考
//1.
public class BankAccount {
private static String acctnum;
private static double money;
private static void showAcct() {
System.out.println("账号为: " + acctnum);
}
private static void showMoney() {
System.out.println("余额为: " + money);
}
public BankAccount(String acc, double m) {
this.acctnum = acc;
this.money = m;
}
public static void main(String[] args) {
BankAccount ba = new BankAccount("626600018888", 5000.00);
ba.showAcct();
ba.showMoney();
}
}
//2.
public class Triangle {
private static float a;
private static float b;
private static float c;
public Triangle(float a, float b, float c) {
this.a = a;
this.b = b;
this.c = c;
}
public static boolean judgeTriangle(float a, float b, float c) {
if ((a Math.abs(b - c) a b + c)
(b Math.abs(a - c) b a + c)
(c Math.abs(a - b) c a + b))
return true;
else
return false;
}
public float getCircumference() {
return this.a + this.b + this.c;
}
}
//3.
public class TestTriangle {
public static void main(String[] args) {
Triangle t = new Triangle(5.3f,7.8f,9.3f);
if(t.judgeTriangle(5.3f,7.8f,9.3f)){
System.out.print("能够成三角形，周长为: ");
System.out.printf("%9.2f",t.getCircumference());}
else
System.out.println("不能构成三角形");
}
}
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class ConstructFrame extends JFrame
{
private static final long serialVersionUID = 1L;
String value1="",result,value2="";
int flag=0,fix=0,sum=1;
Boolean happy;
JTextField text=new JTextField(30);
int flagsum=0;
Container c=getContentPane();
JButton buttonx;
ConstructFrame()
{ super("计算器");
c.setLayout(null);
c.setBackground(Color.blue);
this.setSize(400, 400);
c.add(text);
text.setHorizontalAlignment(JTextField.RIGHT);
final JButton buttonx=new JButton("BackSpace");
c.add(buttonx);
buttonx.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
int count=0;
String temp;
if(flag==0)
{
count=value1.length();
if(count!=1)
temp=value1.substring(0, count-1);
else
temp="0";
value1=temp;
}
else
{
count=value2.length();
if(count!=1)
temp=value2.substring(0, count-1);
else
temp="0";
value2=temp;
}
text.setText(temp);
}
});
final JButton buttony=new JButton("CE");
c.add(buttony);
buttony.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
value1="";
value2="";
flag=0;
text.setText("0");
}
});
final JButton button1=new JButton("1");
c.add(button1);
button1.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+1;
temp=value1;
}
else
{
value2=value2+1;
temp=value2;
}
text.setText(temp);
}
});
final JButton button2=new JButton(" 2 ");
c.add(button2);
button2.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+2;
temp=value1;
}
else
{
value2=value2+2;
temp=value2;
}
text.setText(temp);
}
});
final JButton button3=new JButton("3");
c.add(button3);
button3.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+3;
temp=value1;
}
else
{
value2=value2+3;
temp=value2;
}
text.setText(temp);
}
});
final JButton button4=new JButton("4");
c.add(button4);
button4.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+4;
temp=value1;
}
else
{
value2=value2+4;
temp=value2;
}
text.setText(temp);
}
});
final JButton button5=new JButton("5");
c.add(button5);
button5.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+5;
temp=value1;
}
else
{
value2=value2+5;
temp=value2;
}
text.setText(temp);
}
});
final JButton button6=new JButton("6");
c.add(button6);
button6.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+6;
temp=value1;
}
else
{
value2=value2+6;
temp=value2;
}
text.setText(temp);
}
});
final JButton button7=new JButton("7");
c.add(button7);
button7.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+7;
temp=value1;
}
else
{
value2=value2+7;
temp=value2;
}
text.setText(temp);
}
});
final JButton button8=new JButton("8");
c.add(button8);
button8.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+8;
temp=value1;
}
else
{
value2=value2+8;
temp=value2;
}
text.setText(temp);
}
});
final JButton button9=new JButton("9");
c.add(button9);
button9.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+9;
temp=value1;
}
else
{
value2=value2+9;
temp=value2;
}
text.setText(temp);
}
});
final JButton button0=new JButton("0");
c.add(button0);
button0.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
String temp;
if(flag==0)
{
value1=value1+0;
temp=value1;
}
else
{
value2=value2+0;
temp=value2;
}
text.setText(temp);
}
});
final JButton buttonadd=new JButton(" + ");
c.add(buttonadd);
buttonadd.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
flag=1;
fix=1;
flagsum=0;
}
});
final JButton buttonsubtract=new JButton(" - ");
c.add(buttonsubtract);
buttonsubtract.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
flag=1;
fix=2;
flagsum=0;
}
});
final JButton buttoncheng=new JButton(" * ");
c.add(buttoncheng);
buttoncheng.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
flag=1;
fix=3;
flagsum=0;
}
});
final JButton buttonchu=new JButton(" / ");
c.add(buttonchu);
buttonchu.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
flag=1;
flagsum=0;
fix=4;
}
});
final JButton buttonequal=new JButton(" = ");
c.add(buttonequal);
buttonequal.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
double temp1,temp2;
double temp=0;
flagsum=0;
temp1=Double.parseDouble(value1);
temp2=Double.parseDouble(value2);
flag=0;
switch(fix)
{
case 1: temp=temp1+temp2;break;
case 2: temp=temp1-temp2;break;
case 3: temp=temp1*temp2;break;
case 4: temp=temp1/temp2;break;
}
result=Double.valueOf(temp).toString();
value1=result;
value2="";
flag=1;
text.setText(result);
}
});
final JButton buttonpoint=new JButton(".");
c.add(buttonpoint);
buttonpoint.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{ if(flagsum==0)
{
String temp;
if(flag==0 )
{
value1=value1+".";
temp=value1;
}
else
{
value2=value2+".";
temp=value2;
}
flagsum=1;
text.setText(temp);
}
}
});
JButton buttonz=new JButton("Start");
c.add(buttonz);
buttonz.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{ if(sum%2==1)
{
happy=true;
text.setText("0.");
flag=0;
}
else
{
happy=false;
value1="";
value2="";
text.setText("");
}
text.setEnabled(happy);
button1.setEnabled(happy);
button2.setEnabled(happy);
button3.setEnabled(happy);
button4.setEnabled(happy);
button5.setEnabled(happy);
button6.setEnabled(happy);
button7.setEnabled(happy);
button8.setEnabled(happy);
button9.setEnabled(happy);
button0.setEnabled(happy);
buttonx.setEnabled(happy);
buttony.setEnabled(happy);
buttonadd.setEnabled(happy);
buttonsubtract.setEnabled(happy);
buttonpoint.setEnabled(happy);
buttonequal.setEnabled(happy);
buttoncheng.setEnabled(happy);
buttonchu.setEnabled(happy);
sum++;
}
});
button1.setEnabled(false);
button2.setEnabled(false);
button3.setEnabled(false);
button4.setEnabled(false);
button5.setEnabled(false);
button6.setEnabled(false);
button7.setEnabled(false);
button8.setEnabled(false);
button9.setEnabled(false);
button0.setEnabled(false);
buttonx.setEnabled(false);
buttony.setEnabled(false);
buttonadd.setEnabled(false);
buttonsubtract.setEnabled(false);
buttonpoint.setEnabled(false);
buttonequal.setEnabled(false);
buttoncheng.setEnabled(false);
buttonchu.setEnabled(false);
text.setEnabled(false);
text.setBounds(20, 20, 200, 40);
buttonx.setBounds(20, 60,100, 40);
buttony.setBounds(140, 60,100, 40);
buttonz.setBounds(260, 60,80, 40);
button1.setBounds(20, 120,60, 40);
button2.setBounds(100, 120,60, 40);
button3.setBounds(180, 120,60, 40);
buttonadd.setBounds(260, 120,60, 40);
button4.setBounds(20, 180,60, 40);
button5.setBounds(100, 180,60, 40);
button6.setBounds(180, 180,60, 40);
buttonsubtract.setBounds(260, 180,60, 40);
button7.setBounds(20, 240,60, 40);
button8.setBounds(100, 240,60, 40);
button9.setBounds(180, 240,60, 40);
buttoncheng.setBounds(260,240,60,40);
button0.setBounds(20, 300,60, 40);
buttonpoint.setBounds(100, 300, 60, 40);
buttonequal.setBounds(180,300,60, 40);
buttonchu.setBounds(260, 300,60, 40);
setVisible(true);
}
class MYMouseEvent extends MouseAdapter
{
public void mousePressed(MouseEvent e)
{
value1=e.toString();
text.setText(value1);
}
}
}
class Calutator
{
public static void main(String[] args)
{
new ConstructFrame();
}
}
你自己慢慢的看吧！