Loading a Settings File

Using a Settings.ini file to populate required properties.

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Helper_Load_Properties.java

The following code sample illustrates how to use a settings file to set required properties.

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.Properties;
import java.util.Set;

public class Helper_Load_Properties {
    
    private Properties props;
    
    public Helper_Load_Properties(String file, String args[], boolean verbose) {
        this(file); // Go ahead and invoke the base constructor.
        
        List<String> bad_args = new ArrayList<String>();
        List<String> sad_args = new ArrayList<String>();

        for (int curr_arg = 0; curr_arg < args.length; curr_arg++) {
            
            String arg = "";
            String val = "";
            
            String[] parts = args[curr_arg].split("=");
            
            if (parts.length == 2) {
                arg = parts[0].trim();
                val = parts[1].trim();
                
                if (props.getProperty(arg) == null) {
                    sad_args.add(args[curr_arg]);
                }
                
                props.setProperty(arg, val);
                
            }
            else {
                bad_args.add(args[curr_arg]);
            }
        }
        
        if (verbose) {
            if (bad_args.size() > 0) {
                System.out.println("One or more arguments could not be correctly parsed. These will be ignored:");
                for (int i = 0; i < bad_args.size(); i++) {
                    System.out.println("\t" + bad_args.get(i));
                }
            }
            
            if (sad_args.size() > 0) {
                System.out.println("One or more argument names does not match a pre-existing argument name in the configuration file. These will be applied anyway:");
                for (int i = 0; i < sad_args.size(); i++) {
                    System.out.println("\t" + sad_args.get(i));
                }
            }
            
            if ((bad_args.size() > 0) || (sad_args.size() > 0)) {
                System.out.println("For arguments that contain spaces, surround the entire statement in quotes like, \"user=Eleanor Frisbee\". Argument names and values will have beginning and ending spaces trimmed away. Don't surround values in ' characters.");
            }
        }
        
    }
    
    public Helper_Load_Properties(String file) {
        props = new Properties();
        InputStream input = null;
        
        try {
            input = new FileInputStream(file);
            props.load(input);
        }
        catch (IOException ex) {
            System.out.println("The specified settings file, \"" + file + "\" could not be found.");
        }
        finally {
            if (input != null) {
                try {
                    input.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
    
    public void list() {
        Set<Entry<Object, Object> > set = props.entrySet();
        Iterator<Entry<Object, Object>> iter = set.iterator();
        
        System.out.println("Settings Loaded:");
        while (iter.hasNext()) {
            Entry<Object, Object> ent = iter.next();
            System.out.println("\t" + "arg: " + ent.getKey() + "\t" + "val: " + ent.getValue());
        }
        
    }
    
    public String get(String prop) {
        String retVal = props.getProperty(prop);
        
        if (retVal == null) {
            throw new NullPointerException("The key \"" + prop + "\" does not exist in the configuration file.");
        }
        
        return retVal;
        
    }
    
}