比如你现在有一个可以运行的class文件叫做A.class。那么在命令行中可以这样执行这个程序:
java A arg
其中arg是A需要的参数。那么A是怎么得到这个arg的呢。基本上是这样的:
public static void main(String[] args)
{
if(args.length > 0)
{
String str = arg[0];
}
}
这是在A.java中的main函数,这里只是得到了第一个参数的做法,如果想得到更多的参数,只要做一个简单的循环遍例这个数组args就可以了。
java A arg
其中arg是A需要的参数。那么A是怎么得到这个arg的呢。基本上是这样的:
public static void main(String[] args)
{
if(args.length > 0)
{
String str = arg[0];
}
}
这是在A.java中的main函数,这里只是得到了第一个参数的做法,如果想得到更多的参数,只要做一个简单的循环遍例这个数组args就可以了。
//: NewIODemo.java
// Java 1.1 IO typical usage
import java.io.*;public class NewIODemo {
public static void main(String[] args) {
try {
// 1. Reading input by lines:
BufferedReader in =
new BufferedReader(
new FileReader(args[0]));
String s, s2 = new String();
while((s = in.readLine())!= null)
s2 += s + "\n";
in.close(); // 1b. Reading standard input:
BufferedReader stdin =
new BufferedReader(
new InputStreamReader(System.in));
System.out.print("Enter a line:");
System.out.println(stdin.readLine()); // 2. Input from memory
StringReader in2 = new StringReader(s2);
int c;
while((c = in2.read()) != -1)
System.out.print((char)c); // 3. Formatted memory input
try {
DataInputStream in3 =
new DataInputStream(
// Oops: must use deprecated class:
new StringBufferInputStream(s2));
while(true)
System.out.print((char)in3.readByte());
} catch(EOFException e) {
System.out.println("End of stream");
} // 4. Line numbering & file output
try {
LineNumberReader li =
new LineNumberReader(
new StringReader(s2));
BufferedReader in4 =
new BufferedReader(li);
PrintWriter out1 =
new PrintWriter(
new BufferedWriter(
new FileWriter("IODemo.out")));
while((s = in4.readLine()) != null )
out1.println(
"Line " + li.getLineNumber() + s);
out1.close();
} catch(EOFException e) {
System.out.println("End of stream");
} // 5. Storing & recovering data
try {
DataOutputStream out2 =
new DataOutputStream(
new BufferedOutputStream(
new FileOutputStream("Data.txt")));
out2.writeDouble(3.14159);
out2.writeBytes("That was pi");
out2.close();
DataInputStream in5 =
new DataInputStream(
new BufferedInputStream(
new FileInputStream("Data.txt")));
BufferedReader in5br =
new BufferedReader(
new InputStreamReader(in5));
// Must use DataInputStream for data:
System.out.println(in5.readDouble());
// Can now use the "proper" readLine():
System.out.println(in5br.readLine());
} catch(EOFException e) {
System.out.println("End of stream");
} // 6. Reading and writing random access
// files is the same as before.
// (not repeated here) } catch(FileNotFoundException e) {
System.out.println(
"File Not Found:" + args[1]);
} catch(IOException e) {
System.out.println("IO Exception");
}
}
} ///:~
System.in();
我的方法是
import java.io.*;public class te{
public static void main(String arg[])
{
String aaa;
try{
DataInputStream din=new DataInputStream(System.in);
aaa=din.readLine();
System.out.println(aaa);
}catch(IOException e){}
}
}