import java.util.Map;
 
public class Getenv{
    public static void main(String args[]){
        for (Map.Entry<String, String> env : System.getenv().entrySet()) {
            System.out.println(env.getKey() + " : " + env.getValue());
        }
    }
}

import org.apache.commons.lang.builder.ToStringBuilder;
 
public class VarDump{
    public static void main(String args[]){
        System.out.println(ToStringBuilder.reflectionToString(args));
    }
}

import java.util.Properties;
import java.io.FileInputStream;
 
public class PropertyFile{
    public static void main(String args[]){
        try {
            Properties prop = new Properties();
            prop.load(new FileInputStream("application.ini"));
            for (String propertyName : prop.stringPropertyNames()) {
                System.out.println(propertyName);
                System.out.println(prop.getProperty(propertyName));
            }
        } catch (Exception e){
            e.printStackTrace();
        }
    }
}

hoge=fuga
hello=world

import java.io.File;
import java.io.FilenameFilter;
 
public class ListFiles{
    public static void main(String args[]){
        File directory = new File(args[0]);
        for(File file : directory.listFiles(getRegexFilter(".*\\.xls"))){
            System.out.println(file.getAbsolutePath());
        }
    }
 
    private static FilenameFilter getRegexFilter(String regex) {
        final String regex_ = regex;
        return new FilenameFilter() {
            public boolean accept(File dir, String name) {
                return name.matches(regex_);
            }
        };
    }
}

public class ArrayCopy{
    public static void main(String args[]){
        String[] array = new String[3];
        array[0] = "0";
        array[1] = "1";
        array[2] = "2";
 
        String[] new_array = new String[array.length+1];
 
        //「array(引数1)」の「0(引数2)」番目から「array.length(引数5)」分を「new_array(引数3)」の「0(引数4)」番目以降にコピーする
        System.arraycopy(array, 0, new_array, 0, array.length);
 
        //new_arrayの最後尾に「3」を追加
        new_array[array.length] = "3";
 
        //実行結果
        //0
        //1
        //2
        //3
        for(String str : new_array){
            System.out.println(str);
        }
    }
}