java代码
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初始化
class Tag {
Tag(int marker) {
System.out.println("Tag(" + marker + ")");
}
}
class Card {//无论属性写在类的哪个部分，都首先初始化属性 Tag t1 = new Tag(1); // Before constructor
Card() {
System.out.println("Card()");
t3 = new Tag(33); // Re-initialize t3
}
Tag t2 = new Tag(2); // After constructor
void f() {
System.out.println("f()");
}
Tag t3 = new Tag(3); // At end
}
public class Init {
public static void main(String[] args) {
Card t = new Card();
t.f(); // Shows that construction is done
}
}
结果：Tag(1)
Tag(2)
Tag(3)
Card()
Tag(33)
f()
静态属性初始化
//先初始化静态属性，且只初始化一次
class Bowl {
Bowl(int marker) {
System.out.println("Bowl(" + marker + ")");
}
void f(int marker) {
System.out.println("f(" + marker + ")");
}
}
class Table {
static Bowl b1 = new Bowl(1);
Table() {
System.out.println("Table()");
b2.f(1);
}
void f2(int marker) {
System.out.println("f2(" + marker + ")");
}
static Bowl b2 = new Bowl(2);
}
public class SecondInit {
Table t4 = new Table();
static Table t2 = new Table();
static Table t1 = new Table();
public static void main(String[] args) {
SecondInit si = new SecondInit();
}
}
结果：Bowl(1)
Bowl(2)
Table()
f(1)
Table()
f(1)
Table()
f(1)
IO嵌套写法：
import java.io.*;
public class BufferedStream{
public static void main(String args[]){
try{
File inFile=new File("file1.txt");
File outFile=new File("file2.txt");
FileInputStream fis=new FileInputStream(inFile);
BufferedInputStream bis = new BufferedInputStream(fis);
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(outFile),20);
int c;
int i=1;
while((c=bis.read())!=-1){
bos.write(c);
System.in.read();
System.out.println("写入Buffer第"+i++);
}
bis.close(); bos.close();
}catch(FileNotFoundException e) {
System.out.println("FileStreamsTest: "+e);
}catch(IOException e) {
System.err.println("FileStreamsTest: "+e);
}
}
}
FileOutputStream fos=new FileOutputStream("file2.txt");
BufferedOutputStream bos = new BufferedOutputStream(fos);
DataOutputStream dos=new DataOutputStream (bos); //嵌套写法
import java.io.*;
import .*;
import java.util.*;
public class NetServer1
{
public static final int PORT =8080;
public static void main(String[] args) throws IOException
{
InetAddress addr = InetAddress.getByName("localhost");
ServerSocket s =new ServerSocket(PORT,10,addr);
System.out.println("虚拟Web服务器启动: "+s);
try{
Socket socket =s.accept();
try{
System.out.println("接受客户端连接请求: "+socket);
BufferedReader in = new BufferedReader(
new InputStreamReader(
socket.getInputStream())) ;
PrintWriter out = new PrintWriter(
new BufferedWriter(
new OutputStreamWriter(
socket.getOutputStream())),true);
String str = in.readLine();
byte[] input = new byte[20];
int i = 0;
System.out.println("收到"+(++i)+"条: "+str);
while(str!=null&&!str.equals("END")){
System.in.read(input);
str = in.readLine();
System.out.println("收到"+(++i)+"条: "+str);
}
out.println("客户端传送信息服务器已经接收完毕");
System.out.println("此次服务完毕，开始下轮监听");