书本38面T3，T5
//秋水花数
public class Test1 {
static int sum = 0;
public static void main(String[] args) {
for(int i =100 ; i < 1000 ; i++)
{
int a = i/100 ; //a表示i的百位数值 ；
int b = (i/10)%10 ; //b表示i的十位数值 ；
int c = i % 10; //c表示i的个位数值 ；
if(a*a*a + b*b*b + c*c*c == i)
{
System.out.println(i);
}
}
}
}
//计算1!+2!+...+100!:
public class Test1{
static int sum = 0;
public static void main(String[] args) {
double sum = 0,i = 1,j = 0 ,k = 1;
do{
k = 1;
j = i;
do{
k = k * j;
j--;
}while(j >= 1);
sum = sum + k;
i++;
}while(i <= 100);
System.out.println("1!+2!+...+100! = "+sum);
}
}
书本第60面T1,T2
//complex类:
public class complex {
int realpart;
int imaginpart;
complex() {
realpart = 0;
imaginpart = 0;
}
complex(int r, int i) {
realpart = r;
imaginpart = i;
}
complex complexAdd(complex com) {
return new complex(this.realpart + com.realpart, this.imaginpart + com.imaginpart);
}
}
//Test测试类:
public class Test1 {
public static void main(String[] args) {
complex c[] = new complex[5];
c[1] = new complex(1, 2);
c[2] = new complex(1, -2);
c[3] = new complex(3, 4);
c[4] = new complex(-1, 2);
for (int i = 2; i <= 4; i++) {
c[0] = c[1].complexAdd(c[i]);
System.out.println("(" + c[1].realpart + (c[1].imaginpart < 0 ? "" : "+")
+ c[1].imaginpart + "i)+("
+ c[i].realpart + (c[i].imaginpart < 0 ? "" : "+")
+ c[i].imaginpart + "i)="+ (c[0].realpart == 0 ? (c[0].imaginpart == 0 ? 0 : "") : c[0].realpart)
+ (c[0].imaginpart == 0 ? "" : ((c[0].imaginpart < 0 ? "" : "+") + c[0].imaginpart + "i")));
}
}
}
//Rectangle类:
public class Rectangle {
double width;
double length;
Rectangle(double l, double w) {
check(w, l);
width = w;
length = l;
}
public void check(double w, double l) {
if (w <= 0 || w > 50 || l <= 0 || l > 50) {
System.out.print("长或宽超出规定范围!");
System.exit(0);
}
}
public double getArea() {
return this.length * this.width;
}
public double getPerimeter() {
return (this.length + this.width) * 2;
}
public void Draw() {
for (int i = 1; i <= this.width; i++) {
for (int j = 1; j <= this.length; j++) {
if (i == 1 || i == this.width) {
System.out.print("*");
} else {
if (j == 1 || j == this.length) {
System.out.print("*");
} else {
System.out.print(" ");
}
}
}
System.out.print("n");
}
}
}
// Test测试类:
public class Test1 {
public static void main(String[] args) {
Rectangle rec = new Rectangle(10, 5);
System.out.println("面积:" + rec.getArea());
System.out.println("周长：" + rec.getPerimeter());
rec.Draw();
}
}
课本90，T1,T2
//ShapArea接口:
interface ShapArea {
double getArea();
double getPerimeter();
}
// MyRectangle类:
public class MyRectangle implements ShapArea {
double width;
double height;
public MyRectangle(double w, double h) {
width = w;
height = h;
}
public double getArea() {
return width * height;
}
public double getPerimeter() {
return (width + height) * 2;
}
public String toString() {
System.out.println("width = " + width + " , height = " + height + " , perimeter = " + getPerimeter()
+ " , area = " + getArea());
return "width = " + width + " , height = " + height + " , perimeter = " + getPerimeter() + " , area = "
+ getArea();
}
}
// MyTriangle类:
public class MyTriangle implements ShapArea {
double a, b, c, p;
public MyTriangle(double x, double y, double z) {
a = x;
b = y;
c = z;
p = (a + b + c) / 2;
}
public double getArea() {
return Math.sqrt(p * (p - a) * (p - b) * (p - c));
}
public double getPerimeter() {
return a + b + c;
}
public String toString() {
System.out.println("three sides:" + a + " , " + b + " , " + c + " , perimeter =" + getPerimeter() + " , area = "
+ getArea());
return "three sides:" + a + " , " + b + " , " + c + " , perimeter =" + getPerimeter() + " , area = "
+ getArea();
}
}
// Test测试类:
public class Test1 {
public static void main(String[] args) {
MyRectangle m = new MyRectangle(5, 6);
m.toString();
MyTriangle t = new MyTriangle(3, 4, 5);
t.toString();
}
}
//Area接口
public interface Area {
double CalsulateArea();
}
//MyCircle类
public class MyCircle implements Area {
double radius;
final double PI = 3.1415926;
public MyCircle(double r) {
radius = r;
}
public double CalsulateArea() {
return PI * radius * radius;
}
}
//MyRectangle类
public class MyRectangle implements Area {
double width, height;
public MyRectangle(double w, double h) {
width = w;
height = h;
}
public double CalsulateArea() {
return width * height;
}
}
//Test测试类
public class Test {
public static void main(String[] args) {
MyRectangle m = new MyRectangle(5, 6);
MyCircle m1 = new MyCircle(10);
System.out.println("正方形m的面积:" + m.CalsulateArea() + "n圆形m1的面积:" + m1.CalsulateArea());
}
}
课本183 T2 T4
//第2题
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class Frame2 extends JFrame implements ActionListener {
JButton btn1, btn2;
JTextArea txt;
Frame2() {
this.setBounds(10, 10, 600, 400);
this.setLayout(new FlowLayout(FlowLayout.CENTER));
btn1 = new JButton("按钮btn1");
btn1.addActionListener(this);
btn2 = new JButton("按钮btn2");
btn2.addActionListener(this);
txt = new JTextArea(1, 15);
this.add(txt);
this.add(btn1);
this.add(btn2);
this.setVisible(true);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public static void main(String args[]) {
new Frame2();
}
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if (e.getSource() == btn1) {
txt.setText("按钮btn1");
}
if (e.getSource() == btn2) {
txt.setText("按钮btn2");
}
}
}
public class Point{
double x ,y;
public Point(double x , double y) {
this.x = x;
this.y = y;
}
double getX(){
return x;
}
double getY(){
return y;
}
void setX(double x){
this.x = x;
}
void setY(double y){
this.y = y;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Point p = new Point(10,20);
System.out.println("坐标: ("+p.getX()+","+p.getY()+")");
p.setX(100);
System.out.println("坐标: ("+p.getX()+","+p.getY()+")");
p.setY(200);
System.out.println("坐标: ("+p.getX()+","+p.getY()+")");
}
}
课本207 T3,T4
import java.io.*;
import java.util.*;
public class Test_3 {
public static void main(String[] args) throws Exception {
String fileName = "txt.txt";
System.out.println("输入一个文件名");
Reader is = new InputStreamReader(System.in);
fileName = (new BufferedReader(is)).readLine();
FileInputStream fis = new FileInputStream(fileName);
int ch;
Map ha = new HashMap();
for(int i = 'a'; i <= 'z'; i++){
ha.put((char)i,0);
}
while((ch = fis.read()) != -1){
if(((char)ch >= 'a' && (char)ch <= 'z') || ((char)ch >= 'A' && (char)ch <= 'Z')){
if((char)ch >= 'A' && (char)ch <= 'Z'){
ch = ch + 32;
}
int j = 0;
j = ha.get((char)ch);
ha.put((char)ch,j+1);
}
}
for(int k = 'a'; k <= 'z'; k++){
if(ha.get((char)k) != 0){
System.out.println((char)k + " = " + ha.get((char)k));
}
}
fis.close();
}
}
import java.util.*;
public class Test_4 {
public static void main(String arg[]){
int wordCount=0; //用于统计单词的总个数
Map map=new HashMap();//用于统计各个单词的个数，排序
String sentence="hello,my name is Tom,what is your name?he said:"my name is John"";
StringTokenizer token=new StringTokenizer(sentence);
while(token.hasMoreTokens()){ //循环遍历
wordCount++;
String word=token.nextToken(", ?.!:""''n"); //括号里的字符的含义是说按照,空格 ? . : "" '' n去分割，如果这里你没明确要求，即括号里为空，则默认按照空格，制表符，新行符和回车符去分割
if(map.containsKey(word)){ //HashMap不允许重复的key，所以利用这个特性，去统计单词的个数
int count=map.get(word);
map.put(word, count+1); //如果HashMap已有这个单词，则设置它的数量加1
}
else
map.put(word, 1); //如果没有这个单词，则新填入，数量为1
}
System.out.println("总共单词数："+wordCount);
sort(map); //调用排序的方法，排序并输出！
}
public static void sort(Map map){
List> infoIds = new ArrayList>(map.entrySet());
Collections.sort(infoIds, new Comparator>() {
public int compare(Map.Entry o1, Map.Entry o2) {
return (o2.getValue() - o1.getValue());
}
}); //排序
for (int i = 0; i < infoIds.size(); i++) { //输出
Map.Entry id = infoIds.get(i);
System.out.println(id.getKey()+":"+id.getValue());
}
}
}
