真秘汤巡游链接:JAVA问题，学JAVA的请进。

简单得写一下
1:

import java.io.InputStream;
import java.io.*;

public class Upper {
private void l2u(char c) {
if (c < 97 || c > 122) {
System.out.println("Error !");
}
System.out.println((char) (c - 32));
}

public static void main(String[] args) {
Upper upper = new Upper();
InputStream is = System.in;
try {
char c = (char) (is.read());
upper.l2u(c);
} catch (IOException ex) {
}
}
}

2:

import java.awt.*;
import java.applet.*;
import javax.swing.JButton;
import javax.swing.JTextField;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Factorial extends Applet implements ActionListener {
boolean isStandalone = false;
JButton button = new JButton();
JTextField field = new JTextField();
JTextField field2 = new JTextField();

//Initialize the applet
public void init() {
try {
jbInit();
} catch (Exception e) {
e.printStackTrace();
}
}

//Component initialization
private void jbInit() throws Exception {
button.setBounds(new Rectangle(189, 122, 57, 23));
button.setText("Make");
button.addActionListener(this);
this.setLayout(null);
field.setBounds(new Rectangle(87, 125, 80, 19));
field2.setBounds(new Rectangle(88, 167, 158, 19));
this.add(field);
this.add(button);
this.add(field2);
}

//Get Applet information
public String getAppletInfo() {
return "Applet Information";
}

//Get parameter info
public String[][] getParameterInfo() {
return null;
}

public void actionPerformed(ActionEvent e) {
String s = field.getText();
int bn = s2i(s);
if (bn > 0) {
if (bn <= 20) {
long en = 1;
for (int i = 1; i <= bn; i++) {
en = en * i;
}
field2.setText(en + "");
} else {
field2.setText("Too big(<=20)!");
}
} else {
field2.setText("Error!");
}
}

private int s2i(String s) {
if (s != null && s.length() > 0) {
int size = s.length();
for (int i = 0; i < size; i++) {
char c = s.charAt(i);
if (c < 48 || c > 57) {
return 0;
}
}
return Integer.parseInt(s);
}
return 0;
}
}

3:

import java.awt.BorderLayout;

import javax.swing.JFrame;
import javax.swing.JTextField;
import java.awt.Rectangle;
import javax.swing.JButton;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Score extends JFrame implements ActionListener {

JTextField field = new JTextField();
JTextField field2 = new JTextField();
JButton button = new JButton();

public Score() {
try {
jbInit();
} catch (Exception exception) {
exception.printStackTrace();
}
}

private void jbInit() throws Exception {
getContentPane().setLayout(null);
field.setBounds(new Rectangle(28, 26, 64, 19));
button.setBounds(new Rectangle(109, 24, 73, 23));
button.setText("Make");
button.addActionListener(this);
field2.setBounds(new Rectangle(27, 56, 156, 19));
this.getContentPane().add(field);
this.getContentPane().add(button);
this.getContentPane().add(field2);
this.setSize(200, 120);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

public void actionPerformed(ActionEvent e) {
String s = field.getText();
int bn = s2i(s);
if (bn >= 0) {
if (bn <= 100) {
int en = 0;
if (bn > 0 && bn <= 20) {
en = 1;
}
if (bn > 20 && bn <= 40) {
en = 2;
}
if (bn > 40 && bn <= 60) {
en = 3;
}
if (bn > 60 && bn <= 80) {
en = 4;
}
if (bn > 80 && bn <= 100) {
en = 5;
}
field2.setText(en + "");
} else {
field2.setText("Too big(<=100)!");
}
} else {
field2.setText("Error!");
}
}

private int s2i(String s) {
if (s != null && s.length() > 0) {
int size = s.length();
for (int i = 0; i < size; i++) {
char c = s.charAt(i);
if (c < 48 || c > 57) {
return -1;
}
}
return Integer.parseInt(s);
}
return -1;
}

public static void main(String[] args) {
Score score = new Score();
score.setVisible(true);
}
}

解答 （2):字符界面求n的阶乘，楼主自己转换成Applet把

public class Function { //求n的阶乘,递归实现
public static void main(String[] args) {
Function function = new Function();
System.out.println("请输入要求阶乘的n值:");
int n = SavitchIn.readLineInt();
System.out.println(n + "的阶乘" + n + "!=" + function.function(n));
}

public int function(int n) { //递归方法
if (n == 0) { //终止条件
return 1;
} else { //递归条件
return function(n - 1) * n;
}
}
}