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包含pl0编译器java代码的词条
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编写Java程序，要求在命令行窗口输出二十六个英文字母的大小写。
public class PrintLetter
{
public static void main(String args [])
{
PrintLetter pl = new PrintLetter();
pl.printLowerCase ();
pl.printUpperCase ();
}
void printLowerCase ()
{
System.out.println("\n");
char a='a';
for(int i=0;i26;i++)
{
System.out.print(a+" ");
a++;
}
}
void printUpperCase ()
{
System.out.println("\n");
char a='A';
for(int i=0;i26;i++)
{
System.out.print(a+" ");
a++;
}
}
}
相关问答
Q1: 要用java编的计算器代码
给你一个比较简单的吧。以前写的。
共两个类。还只是完成＋、－、×、÷运算而已。
GUI只是用了AWT，很简单，相信一看就能懂了。
Calculator.java
public class Calculator{
private String result = "0";
private int op = 0,add = 1,sub = 2,mul = 3,div = 4;
private double stringToDouble(String x){
double y = Double.parseDouble(x);
return y;
}
private void operate(String x){
double x1 = stringToDouble(x);
double y = stringToDouble(result);
switch (op){
case 0:
result = x;
break;
case 1:
result = String.valueOf(y+x1);
break;
case 2:
result = String.valueOf(y-x1);
break;
case 3:
result = String.valueOf(y*x1);
break;
case 4:
if(x1!=0){
result = String.valueOf(y/x1);
}else{
result = "The divisor can't be zero!";
}
break;
}
}
public String opAdd(String x){
operate(x);
op = add;
return result;
}
public String opSubtract(String x){
operate(x);
op = sub;
return result;
}
public String opMultiply(String x){
operate(x);
op = mul;
return result;
}
public String opDivide(String x){
operate(x);
op = div;
return result;
}
public String opEquals(String x){
operate(x);
op = 0;
return result;
}
public void opClean(){
op = 0;
result = "0";
}
}
CalculatorGUI.java
import java.awt.*;
import java.awt.event.*;
import java.util.EventObject;
public class CalculatorGUI{
private Frame f;
private Panel p1,p2;
private Button b0,b1,b2,b3,b4,b5,b6,b7,b8,b9;
private Button bPoint,bAdd,bDec,bMul,bDiv,bCal;
private TextField tf;
private String s,op;
private Calculator cal = new Calculator();
private boolean ifOp;
public CalculatorGUI(){
f = new Frame("Calculator");
p1 = new Panel();
p2 = new Panel();
b0 = new Button("0");
b1 = new Button("1");
b2 = new Button("2");
b3 = new Button("3");
b4 = new Button("4");
b5 = new Button("5");
b6 = new Button("6");
b7 = new Button("7");
b8 = new Button("8");
b9 = new Button("9");
bPoint = new Button(".");
bAdd = new Button("+");
bDec = new Button("-");
bMul = new Button("*");
bDiv = new Button("/");
bCal = new Button("=");
tf = new TextField(25);
tf.setEditable(false);
}
public void launchFrame(){
f.setSize(220,160);
f.setResizable(false);
f.addWindowListener(new myWindowListener());
p1.setLayout(new FlowLayout(FlowLayout.CENTER));
p1.add(tf);
f.add(p1,BorderLayout.NORTH);
p2.setLayout(new GridLayout(4,4));
b0.addActionListener(new setLabelText_ActionListener());
b1.addActionListener(new setLabelText_ActionListener());
b2.addActionListener(new setLabelText_ActionListener());
b3.addActionListener(new setLabelText_ActionListener());
b4.addActionListener(new setLabelText_ActionListener());
b5.addActionListener(new setLabelText_ActionListener());
b6.addActionListener(new setLabelText_ActionListener());
b7.addActionListener(new setLabelText_ActionListener());
b8.addActionListener(new setLabelText_ActionListener());
b9.addActionListener(new setLabelText_ActionListener());
bPoint.addActionListener(new setLabelText_ActionListener());
bAdd.addActionListener(new setOperator_ActionListener());
bDec.addActionListener(new setOperator_ActionListener());
bMul.addActionListener(new setOperator_ActionListener());
bDiv.addActionListener(new setOperator_ActionListener());
bCal.addActionListener(new setOperator_ActionListener());
p2.add(b7);
p2.add(b8);
p2.add(b9);
p2.add(bAdd);
p2.add(b4);
p2.add(b5);
p2.add(b6);
p2.add(bDec);
p2.add(b1);
p2.add(b2);
p2.add(b3);
p2.add(bMul);
p2.add(b0);
p2.add(bPoint);
p2.add(bCal);
p2.add(bDiv);
f.add(p2,BorderLayout.SOUTH);
f.setVisible(true);
}
public void setTextFieldText_Temp(){
if (tf.getText().length()15 (tf.getText().indexOf(".")==-1 || !s.equals("."))){
tf.setText(tf.getText()+s);
}else{
tf.setText((tf.getText()+s).substring(0,15));
}
}
public void setTextFieldText(){
if(ifOp){
ifOp = false;
tf.setText("");
setTextFieldText_Temp();
}else{
setTextFieldText_Temp();
}
}
public static void main(String[] args){
CalculatorGUI calculator = new CalculatorGUI();
calculator.launchFrame();
}
class myWindowListener extends WindowAdapter{
public void windowClosing(WindowEvent e){
System.exit(0);
}
}
class setLabelText_ActionListener implements ActionListener{
public void actionPerformed(ActionEvent e){
Button tempB = (Button)e.getSource();
s = tempB.getLabel();
setTextFieldText();
}
}
class setOperator_ActionListener implements ActionListener{
public void actionPerformed(ActionEvent e){
Button tempB = (Button)e.getSource();
op = tempB.getLabel();
if(op.equals("+")){
tf.setText(cal.opAdd(tf.getText()));
ifOp = true;
}else if(op.equals("-")){
tf.setText(cal.opSubtract(tf.getText()));
ifOp = true;
}else if(op.equals("*")){
tf.setText(cal.opMultiply(tf.getText()));
ifOp = true;
}else if(op.equals("/")){
tf.setText(cal.opDivide(tf.getText()));
ifOp = true;
}else if(op.equals("=")){
tf.setText(cal.opEquals(tf.getText()));
ifOp = true;
}
}
}
}
Q2: 用java代码实现Oracle数据库的备份与恢复(保存为.dmp或.sql)
备份：发送sql给mssqlserver:
backup database your database name to disk='备份文件名' with init
注意: 1.备份文件名必须为绝对路径，
2.备份文件只能是mssqlserver所在的机器上的路径, mssql支持备份到网络位置。
恢复：
restore database your database name from disk='备份文件名' with replace
要注意的是执行restore database时，要恢复的数据库必须没有任何客户端连接，包括自身(发起restore database命令的连接)。发使用restore，可以连接到master库，然后再发送restore命令。
否则，一定失败。
在jsp中如何用呢
-------------------------------------------------------------------------------------- 你用这个了!
%
先要连接上Connection对象!
就是要先和数据库建立起连接
然后在jsp页面中直接用我这样的语句就可以了
try{
String sql="backup database xncsims to disk='d:\\xncback.dat'";
st=con.createStatement();
rs=st.executeQuery(sql);
}
catch(SQLException e){ System.out.println(e.toString());}
catch(Exception e){ System.out.println(e.toString());}
%
rs=st.executeQuery(sql);
这里就是把你的SQL语句发到数据库执行
另有一篇论文供参考
