System.out：标准输出设备（默认是：控制台）

System.in：标准输入设备（默认是：键盘）

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InputStream in = System.in;

int by = in.read();

sysout(by);

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InputStream in = System.in;

StringBuilder sb = new StringBuilder();

while(true){

int ch = in.read();

if(ch==’\r’){

continue;

}

if(ch==’\n’){

String s = sb.toString();

if(“over”.equals(s)){

break;

}

System.out.prinltn(s.toUpperCase());

sb.delete(0, sb.length());

}

else

sb.append((char)ch);

}