在大家开发java程序的时候，往往都会用到一些代码段，而这些代码都可以很好的帮助程序员开发程序，那接下来，我们就来给大家分享一些java编程代码。大家可以参考以下。
1.向文件末尾添加内容
BufferedWriter out = null;
try
{
out = new BufferedWriter(new FileWriter(”filename”, true));
out.write(”aString”);
}
catch (IOException e)
{
// error processing code
}
finally
{
if (out != null)
{
out.close();
}
}2.得到当前方法的名字
String methodName = Thread.currentThread().getStackTrace()[1].getMethodName();
3. 转字符串到日期
java.util.Date = java.text.DateFormat.getDateInstance().parse(date String);
//或者是：
SimpleDateFormat format = new SimpleDateFormat( "dd.MM.yyyy" ); Date date = format.parse( myString );
4.把 Java util.Date 转成 sql.Date
java.util.Date utilDate = new java.util.Date(); java.sql.Date sqlDate = new java.sql.Date(utilDate.getTime());
5. 使用NIO进行快速的文件拷贝
public static void fileCopy(File in , File out)
throws IOException
{
FileChannel inChannel = new FileInputStream( in )
.getChannel();
FileChannel outChannel = new FileOutputStream(out)
.getChannel();
try
{
// inChannel.transferTo(0, inChannel.size(), outChannel); // original -- apparently has trouble copying large files on Windows
// magic number for Windows, 64Mb - 32Kb)
int maxCount = (64 * 1024 * 1024) - (32 * 1024);
long size = inChannel.size();
long position = 0;
while (position < size)
{
position += inChannel.transferTo(position, maxCount, outChannel);
}
}
finally
{
if (inChannel != null)
{
inChannel.close();
}
if (outChannel != null)
{
outChannel.close();
}
}
}6.抓屏程序
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import java.io.File;
...
public void captureScreen(String fileName) throws Exception
{
Dimension screenSize = Toolkit.getDefaultToolkit()
.getScreenSize();
Rectangle screenRectangle = new Rectangle(screenSize);
Robot robot = new Robot();
BufferedImage image = robot.createScreenCapture(screenRectangle);
ImageIO.write(image, "png", new File(fileName));
}
...7.把 Array 转换成 Map
import java.util.Map;
import org.apache.commons.lang.ArrayUtils;
public class Main
{
public static void main(String[] args)
{
String[][] countries = {
{
"United States"
, "New York"
}
, {
"United Kingdom"
, "London"
}
, {
"Netherland"
, "Amsterdam"
}
, {
"Japan"
, "Tokyo"
}
, {
"France"
, "Paris"
}
};
Map countryCapitals = ArrayUtils.toMap(countries);
System.out.println("Capital of Japan is " + countryCapitals.get("Japan"));
System.out.println("Capital of France is " + countryCapitals.get("France"));
}
}8.单实例Singleton 示例
public class SimpleSingleton
{
private static SimpleSingleton singleInstance = new SimpleSingleton();
//Marking default constructor private
//to avoid direct instantiation.
private SimpleSingleton()
{}
//Get instance for class SimpleSingleton
public static SimpleSingleton getInstance()
{
return singleInstance;
}
}这些都是在实际工作中经常用到的代码，大家可以将这些收藏，方便以后开发程序的时候拿出来使用!最后大家如果想要了解更多java初识知识，敬请关注奇Q工具网。
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