printstream.println()的作用是什么？
可以从某个端口 写数据吗？
------解决方案--------------------
PrintStream类中的println方法是打印出文本信息
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http://zhidao.baidu.com/question/51736225.html
------解决方案--------------------
void println()
Terminates the current line by writing the line separator string.
void println(boolean x)
Prints a boolean and then terminate the line.
void println(char x)
Prints a character and then terminate the line.
void println(char[] x)
Prints an array of characters and then terminate the line.
void println(double x)
Prints a double and then terminate the line.
void println(float x)
Prints a float and then terminate the line.
void println(int x)
Prints an integer and then terminate the line.
void println(long x)
Prints a long and then terminate the line.
void println(Object x)
Prints an Object and then terminate the line.
void println(String x)
Prints a String and then terminate the line.