source: sample/hadoop-0.16/test.java @ 31

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.StringTokenizer;

import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapred.JobConf;


// this example is testing for static valiable value
// it will show the value of static valiable is related to Class, not object

class testb {
  // object variable
  public void read() {
    System.out.println(test.sna);
  }
}

public class test {
  int na;
  static int sna;
  static String str;
  public test() {
  }

  public test(String st) {
    str = st;
  }

  public test(int a, int b, String st) {
    na = a;
    sna = b;
    str = st;
  }

  public void print(String str) {
    System.out.println(str);
  }

  @SuppressWarnings( { "static-access" })
  public void strToken() throws IOException {
    test a = new test(1, 2, "a");
    a.print("a.na = " + a.na);
    a.print("test.sna = " + test.sna);

    a.print("a.sna = " + a.sna); // warning about it's not a regular
    // accessing method

    test b = new test(3, 4, "a");
    b.print("b.na = " + b.na);
    b.print("test.sna = " + test.sna);
    b.print("b.sna = " + b.sna); // warning about it's not a regular
    // accessing method

    a.print("a.sna = " + a.sna); // a.sna = test.sna -> b.sna
    String tmp[] = test.str.split(":");
    String Column_Family = tmp[0] + ":";
    a.print("column family = " + Column_Family);
    a.print("ori str = " + test.str);
    // test fileoutputstream
    FileOutputStream out = new FileOutputStream(new File(
        "/home/waue/mr-result.txt"));
    out.write("hello".getBytes());
    out.close();
    // test randomaccessfile
    RandomAccessFile raf = new RandomAccessFile("/home/waue/mr-result.txt",
        "rw");
    raf.seek(raf.length()); // move pointer to end
    raf.write("\n go \t ahead".getBytes());
    raf.close();
    // test StringTokenizer
    StringTokenizer st = new StringTokenizer("this is a test");
    while (st.hasMoreTokens()) {
      System.out.println(st.nextToken());
    }
  }

  String parseFirstLine(String in, String ou) throws IOException {
    BufferedReader fi = new BufferedReader(new FileReader(new File(in)));
    BufferedWriter fw = new BufferedWriter(new FileWriter(new File(ou)));
    String first_line, data;
    first_line = fi.readLine();
    do {
      data = fi.readLine();
      if (data == null) {
        break;
      } else {
        fw.write(data + "\n");
      }
    } while (true);
    fw.close();
    return first_line;
  }

  boolean deleteFile(String str) throws IOException {
    File ttt = new File(str);
    if (ttt.exists()) {
      if (!ttt.delete()) {
        System.err.print("delete file error !");
      }
    } else {
      System.out.println("file not exit!");
    }
    return true;
  }

  void ttt() throws IOException {
    Path pi;
    JobConf conf = new JobConf(test.class);
    FileStatus[] fi = FileSystem.get(conf).listStatus(
        new Path("/user/waue/input/"));
    for (int i = 0; i < fi.length; i++) {
      pi = fi[i].getPath();
      System.out.println(pi.getName());
    }
  }

  public static void main(String[] args) throws IOException {
    // test a = new test();
    // a.strToken();
    // System.out.println(a.parseFirstLine("/home/waue/test.txt",
    // "/home/waue/out.tmp.txt"));
    // ttt();
    
    
    animal a = new animal();
    bird b = new bird();
    dog d = new dog(b);
    animal aaa = new bird();
//    dog ddd = new animal();  -> error 
    
    animal aa = (animal) b;
    System.out.println(aa.hand);
    System.out.println(aa.mind);    
//    bird bb = (bird) a; -> error
//    d.setbird(aa); -> error
//    System.out.println(aa.feather); -> error

    // Fu <T>
    Fu<? extends String> ak;
    ak = new Fu<String>();
    ak.getFu();
    Fu<?> in = ak;
//    in.setFu("ss"); -> error
    in.getFu();
  }
}
class Fu <T>{
  T go;
  void setFu(T go){
    this.go = go;
  }
  T getFu(){
    return go;
  }
}

class animal{
  String head = "head";
  String feet = "feet";
  String body = "body";
  String hand = "head";
  String mind = "mind";
  int id = 1234567;
}
class bird extends animal{
  String feather = "feather";
  bird(){
    hand = "wing";
    id = 1234568;
    System.out.println(head + hand + body + feet + "id="+id);
    System.out.println("super = " + super.hand +"this = " + this.hand);
  }
}
class dog extends animal{
  dog(animal a){
    System.out.println(a.head + hand + body + feet + "id="+id);
  }
  void setbird(bird b){
    System.out.println(b.head + hand + body + feet + "id="+id);
  }
}