// 得到当前方法的名字    public static void getName() {        System.out.println(Thread.currentThread().getStackTrace()[1]                .getMethodName());    }    // 截屏    public static void captureScreen() {        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();        Rectangle screenRectangle = new Rectangle(screenSize);        try {            Robot robot = new Robot();            BufferedImage image = robot.createScreenCapture(screenRectangle);            ImageIO.write(image, "png", new File("jieping.png"));        } catch (AWTException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    // 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 {            // magic number for windows, 64M-32Kb            int maxCount = (64 * 1024 * 1024) - (32 * 1024);            long size = inChannel.size();            long position = 0;            while (position < size) {                position += inChannel                        .transferTo(position, maxCount, outChannel);            }        } catch (Exception e) {            e.printStackTrace();        } finally {            if (inChannel != null) {                inChannel.close();            }            if (outChannel != null) {                outChannel.close();            }        }    }    // 创建json格式数据    //依赖jar:    public static void demoJson() {        JSONObject json = new JSONObject();        json.put("city", "shanghai");        json.put("name", "earic");        System.out.println(json.toString());    }    // 设置http代理    public static void setProxy() {        System.getProperties().put("http.proxyHost", "43.82.218.50");        System.getProperties().put("http.proxyPort", "8080");        System.getProperties().put("http.proxyUser", "ap\5109v20459");        System.getProperties().put("http.proxyPassword", "qazxsw12");        try {            URL url = new URL("http://www.baidu.com");            URLConnection conn = url.openConnection();            String str = conn.getHeaderField(0);            if(str.indexOf("OK")>0){                System.out.println("ok connetcted……");            }else{                System.out.println("error……");            }        } catch (Exception e) {            e.printStackTrace();        }    }    //列出文件和目录    public static void listFiles(){        File dir = new File("C:\\Users\\spring\\workspace\\newsisAP");        String[] children = dir.list();        if(children == null){            System.out.println("error……");        }else{            for(int i=0;i

 

java怎么用一行代码初始化ArrayList1、ArrayList
     
       places = new ArrayList
      
       (Arrays.asList("Buenos Aires", "Córdoba", "La Plata"));2、Java 7 中的列表中文字：List
       
         list = ["A", "B", "C"];3、List
        
          places = Arrays.asList("Buenos Aires", "Córdoba", "La Plata");4、ArrayList arrList = new ArrayList() {"1",2,3,"4" };5、List
         
           strings = asList("foo", "bar", "baz");6、若要设置列表填充 N 的默认对象的副本：ArrayList
          
         
        
       
      
     

 

过滤文件import java.io.File;import java.io.FilenameFilter;public class FileFilterDemo {    public static void main(String[] args) throws Exception {        File f = new File("D:\\workspace\\JavaTest\\src\\demo");        File[] files = f.listFiles(new FilenameFilter(){            public boolean accept(File dir, String name) {                return name.endsWith(".java");            }        });        for (File a : files) {            System.out.println(a.getName());        }    }}

//遍力    String[] strings = {"A", "B", "C", "D"};        Collection stringList = java.util.Arrays.asList(strings);        /* 开始遍历 */        for (Iterator itr = stringList.iterator(); itr.hasNext();) {        Object str = itr.next();        System.out.println(str);        }//禁止重新赋值    int[] integers = {1, 2, 3, 4};    for (final int i : integers) {        //i = i / 2; /* 编译时出错 */ //注意,这只是禁止了对循环变量进行重新赋值。给循环变量的属性赋值,或者调用能让循环变量的内容变化的方法,是不被禁止的        System.out.println(i);    }//允许修改状态    Random[] randoms = new Random[]{
   new Random(1), new Random(2), new Random(3)};    for (final Random r : randoms) {        r.setSeed(4);/* 将所有Random对象设成使用相同的种子 */        System.out.println(r.nextLong());/* 种子相同,第一个结果也相同 */    }

 

catch (Exception e) {    StringWriter errors = new StringWriter(); e.printStackTrace(new PrintWriter(errors));     log.error(errors.toString());    return null;}

 

//静态内部类public class Singleton {        private static class LazyHolder {           private static final Singleton INSTANCE = new Singleton();        }        private Singleton (){}        public static final Singleton getInstance() {           return LazyHolder.INSTANCE;        }    }