1 import java.util.Scanner;
2 /**
3 * @author Administrator
4 * 从控制台输入字符串，将之全部替换成*号输出
5 */
6 public class test1 {
7 static Scanner input = new Scanner(System.in);
8 public static void main(String[] args) {
9 System.out.println("请输入英文字符：");
10 String str = input.next();
11 StringBuffer sb = new StringBuffer(str);
12 for(int i = 0;i<sb.length();i++) {
13 sb.replace(i, i+1, "*");
14 }
15 System.out.println("替换后的字符串为：\n"+sb);
16 }
17 }
1 import java.util.Scanner;
2
3 /**
4 * @author Administrator
5 * 截取一段字符串中的数字
6 */
7 public class Test2 {
8 static Scanner input = new Scanner(System.in);
9 public static void main(String[] args) {
10 System.out.println("请输入字符串：");
11 String str = input.next();
12 StringBuffer num = new StringBuffer();
13 for(int i = 0;i<str.length();i++) {
14 if(str.charAt(i)>=48 && str.charAt(i)<=57) {
15 num.append(str.charAt(i));
16 }
17 }
18 System.out.println("您的字符串包含以下数字：\n"+num.toString());
19 }
20 }
1 import java.util.Scanner;
2
3 /**
4 * @author Administrator
5 * 实现简易字符串压缩算法：一个长度最大为128的字符串，由字母a-z或者A-Z组成，
6 * 将其中连续出现2次以上（含2次）的字母转换为字母和出现次数，
7 */
8 public class Test3 {
9 static Scanner input = new Scanner(System.in);
10 public static void main(String[] args) {
11 System.out.println("请输入一串出英文：");
12 String str = input.next()+" ";
13 StringBuffer sb = new StringBuffer();
14 int num = 1;
15 int i = 0;
16 while(i<str.length()-1) {
17 if(str.charAt(i) == str.charAt(i+1)) {
18 num++;
19 i++;
20 }else if(num>1){
21 sb.append(str.charAt(i));
22 sb.append(num);
23 num=1;
24 i++;
25 }else {
26 sb.append(str.charAt(i));
27 i++;
28 }
29 }
30 System.out.println(sb);
31 }
32 }
1 import java.io.BufferedReader;
2 import java.io.BufferedWriter;
3 import java.io.File;
4 import java.io.FileNotFoundException;
5 import java.io.FileReader;
6 import java.io.FileWriter;
7 import java.io.IOException;
8 import java.util.Scanner;
9
10 /**
11 * @author Administrator
12 * 文件创建及写入与复制
13 */
14 public class Test4 {
15 static Scanner input = new Scanner(System.in);
16 public static void main(String[] args) {
17 String src = "c:/javabigdata/a.txt";
18 String dest = "c:/javabigdata/b.txt";
19 createFile(src);
20 System.out.println("请输入需要保存的内容：");
21 String s = input.next();
22 Out(src,s);
23
24 copy(src,dest);
25 }
26 //新建目录及文件
27 public static void createFile(String str) {
28 File file = new File(str);
29 try {
30 file.createNewFile();
31 } catch (IOException e) {
32 // TODO Auto-generated catch block
33 e.printStackTrace();
34 }
35 }
36
37 //写入数据
38 public static void Out(String str,String s) {
39 BufferedWriter bw = null;
40 FileWriter fw = null;
41 try {
42 fw = new FileWriter(str);
43 bw = new BufferedWriter(fw);
44 bw.write(s);
45 } catch (IOException e) {
46 // TODO Auto-generated catch block
47 e.printStackTrace();
48 }finally {
49 try {
50 bw.flush();
51 bw.close();
52 } catch (IOException e) {
53 // TODO Auto-generated catch block
54 e.printStackTrace();
55 }
56 }
57 }
58
59 //复制文件
60 public static void copy(String src,String dest) {
61 BufferedReader in = null;
62 BufferedWriter out = null;
63 try {
64 in = new BufferedReader(new FileReader(src));
65 out = new BufferedWriter(new FileWriter(dest));
66
67 String line = null;
68 while ( (line = in.readLine()) != null ) {
69 out.write(line);
70 out.newLine();
71 }
72 out.flush();
73 } catch (FileNotFoundException e) {
74 // TODO Auto-generated catch block
75 e.printStackTrace();
76 } catch (IOException e) {
77 // TODO Auto-generated catch block
78 e.printStackTrace();
79 }finally {
80 try {
81 out.close();
82 in.close();
83 } catch (IOException e) {
84 // TODO Auto-generated catch block
85 e.printStackTrace();
86 }
87
88 }
89 }
90 }
1 import java.text.SimpleDateFormat;
2 import java.util.Date;
3
4 /**
5 * @author Administrator
6 * 在控制台不断按时分秒打印的电子表
7 */
8 public class Test5 {
9 public static void main(String[] args) {
10 SimpleDateFormat format = new SimpleDateFormat("HH:mm:ss");
11 while(true) {
12 String time = format.format(new Date());
13 System.out.println(time);
14 try {
15 Thread.sleep(1000);
16 } catch (InterruptedException e) {
17 // TODO Auto-generated catch block
18 e.printStackTrace();
19 }
20 }
21 }
22 }
1 /**
2 * @author Administrator
3 * 两个线程模拟两个人【一个实现runnable接口，一个继承thread类】，分别叫jack和rose，模拟两人在对话1000次
4 */
5 public class Test6Dome {
6 public static void main(String[] args) {
7 Test6Syn syn = new Test6Syn();
8
9 Test6Thread num = new Test6Thread(syn);
10 Test6Runnable num1 = new Test6Runnable(syn);
11
12 Thread thread = new Thread(num);
13 Thread thread1 = new Thread(num1);
14
15 thread.start();
16 thread1.start();
17 }
18 }
19
20
21 实现Runnable
22 public class Test6Runnable implements Runnable{
23 private Test6Syn syn;
24
25 public Test6Runnable(Test6Syn syn) {
26 super();
27 this.syn = syn;
28 }
29
30 public void run() {
31 while(true) {
32 for(int i = 0;i<500;i++) {
33 syn.num1();
34 }
35 break;
36 }
37 }
38
39 }
40
41 继承Thread
42 public class Test6Thread extends Thread{
43 private Test6Syn syn;
44
45 public Test6Thread(Test6Syn syn) {
46 super();
47 this.syn = syn;
48 }
49
50 public void run() {
51 while(true) {
52 for(int i = 0;i<500;i++) {
53 syn.num();
54 }
55 break;
56 }
57 }
58 }
59
60 唤醒机制
61 public class Test6Syn {
62 private boolean flag = false;
63 public synchronized void num() {
64 if(flag) {
65 try {
66 wait();
67 } catch (InterruptedException e) {
68 // TODO Auto-generated catch block
69 e.printStackTrace();
70 }
71 }
72 System.out.println("jack说：我是查水表的！");
73 flag = true;
74 this.notify();
75 }
76
77 public synchronized void num1() {
78 if(!flag) {
79 try {
80 wait();
81 } catch (InterruptedException e) {
82 // TODO Auto-generated catch block
83 e.printStackTrace();
84 }
85 }
86 System.out.println("rose说：你是谁啊？");
87 flag = false;
88 this.notify();
89 }
90 }
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Test7Dome {
static Scanner input = new Scanner(System.in);
public static void main(String[] args) {
List<Penguin> list = new ArrayList<>();
list.add(new Penguin("欧欧", "Q仔"));
list.add(new Penguin("亚亚", "Q妹"));
list.add(new Penguin("菲菲", "Q妹"));
list.add(new Penguin("美美", "Q妹"));
System.out.println("共计有" + list.size() + "只企鹅。\n分别是：");
for (Penguin p : list) {
System.out.println(p.getName() + "\t" + p.getSex());
}
System.out.println("请输入要删除的企鹅名字：");
String name = input.next();
int dex =-1;
for (int i = 0; i < list.size(); i++) {
if (list.get(i).getName().equals(name)) {
list.remove(i);
dex = i;
}
}
if(dex!=-1) {
System.out.println("删除成功！");
}else {
System.out.println("不存在！");
}
System.out.println("删除之后还有" + list.size() + "只企鹅\n" +"分别是：");
for (Penguin p : list) {
System.out.println(p.getName() + "\t" + p.getSex());
}
System.out.println("请输入要查找的企鹅名字：");
String name1 = input.next();
int dex1 =-1;
for (int i = 0; i < list.size(); i++) {
if (list.get(i).getName().equals(name1)) {
dex1 = i;
}
}
if(dex1!=-1) {
System.out.println("集合中包含" + name1 + "的信息");
}else {
System.out.println("集合中不包含" + name1 + "的信息");
}
}
}
1 import java.util.Scanner;
2
3 /**
4 * @author Administrator
5 * 会员注册
6 */
7 public class Test8 {
8 static Scanner input = new Scanner(System.in);
9 static boolean flag = false;
10 public static void main(String[] args) {
11 System.out.println("***欢迎进入注册系统***");
12 while(!flag) {
13 System.out.println("请输入用户名：");
14 String name = input.next();
15 System.out.println("请输入密码：");
16 String psw = input.next();
17 System.out.println("请再次输入密码：");
18 String psw1 = input.next();
19 flag = isOk(name,psw,psw1);
20 }
21
22 }
23
24 public static boolean isOk(String name,String psw,String psw1) {
25 if(name.length()<3||psw.length()<6) {
26 flag = false;
27 System.out.println("用户名长度不嫩小于3，密码长度不能小于6！");
28 }else if(!psw.equals(psw1)) {
29 flag = false;
30 System.out.println("两次输入的密码不相同！！");
31 }else {
32 flag = true;
33 System.out.println("注册成功！");
34 }
35 return flag;
36
37 }
38 }
1 import java.io.BufferedReader;
2 import java.io.IOException;
3 import java.io.InputStream;
4 import java.io.InputStreamReader;
5 import java.io.OutputStream;
6 import java.net.ServerSocket;
7 import java.net.Socket;
8
9 /**
10 * @author Administrator
11 * 服务器端
12 */
13 public class Test9Sever {
14 public static void main(String[] args) {
15 try {
16 ServerSocket serversocket = new ServerSocket(8888);
17 Socket socket = serversocket.accept();
18 InputStream is = socket.getInputStream();
19 BufferedReader br = new BufferedReader(new InputStreamReader(is));
20 String info;
21 while((info = br.readLine())!=null) {
22 System.out.println("客户端说："+info);
23 }
24
25 String reply = "欢迎！";
26 OutputStream ot = socket.getOutputStream();
27 ot.write(reply.getBytes());
28
29 ot.close();
30 br.close();
31 is.close();
32 socket.close();
33 serversocket.close();
34 } catch (IOException e) {
35 // TODO Auto-generated catch block
36 e.printStackTrace();
37 }
38 }
39 }
40
41
42 import java.io.BufferedReader;
43 import java.io.BufferedWriter;
44 import java.io.IOException;
45 import java.io.InputStream;
46 import java.io.InputStreamReader;
47 import java.io.OutputStream;
48 import java.net.Socket;
49
50 /**
51 * @author Administrator
52 * 客户端
53 */
54 public class Test9Client {
55 public static void main(String[] args) {
56 try {
57 Socket socket = new Socket("localhost",8888);
58 String info = "用户名：Dean，密码：123456";
59 OutputStream os = socket.getOutputStream();
60 os.write(info.getBytes());
61
62 socket.shutdownOutput();
63 InputStream is = socket.getInputStream();
64 BufferedReader br = new BufferedReader(new InputStreamReader(is));
65 String info1;
66 while((info1 = br.readLine())!=null) {
67 System.out.println("服务器说："+info1);
68 }
69
70 br.close();
71 is.close();
72 os.close();
73 socket.close();
74 } catch (IOException e) {
75 // TODO Auto-generated catch block
76 e.printStackTrace();
77 }
78 }
79 }
1 import java.io.BufferedInputStream;
2 import java.io.BufferedOutputStream;
3 import java.io.FileInputStream;
4 import java.io.FileNotFoundException;
5 import java.io.FileOutputStream;
6 import java.io.IOException;
7
8 /**
9 * @author Administrator
10 * 图片复制
11 */
12 public class Test10 {
13 public static void main(String[] args) {
14 copy("a.png","b.png");
15 }
16
17 private static void copy(String src, String dest){
18 BufferedInputStream in = null;
19 BufferedOutputStream out = null;
20 try {
21 in = new BufferedInputStream(new FileInputStream(src));
22 out = new BufferedOutputStream(new FileOutputStream(dest));
23 byte[] buffer = new byte[1024];
24 int len = -1;
25 while ( (len = in.read(buffer)) != -1) {
26 out.write(buffer, 0, len);
27 }
28 } catch (FileNotFoundException e) {
29 // TODO Auto-generated catch block
30 e.printStackTrace();
31 } catch (IOException e) {
32 // TODO Auto-generated catch block
33 e.printStackTrace();
34 }finally {
35 try {
36 in.close();
37 out.close();
38 } catch (IOException e) {
39 // TODO Auto-generated catch block
40 e.printStackTrace();
41 }
42 }
43 }
44 }
来源：https://www.cnblogs.com/Dean-0/p/11340896.html