JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: How to get all keys from properties file?


Description:

This example shows how to get all keys from the given properties file. All keys will be returned in the form of set object. You can get it by calling keySet() method.


Code:
package com.java2novice.properties;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.util.Set;

public class MyPropAllKeys {

	private Properties prop = null;
	
	public MyPropAllKeys(){
		
		InputStream is = null;
		try {
			this.prop = new Properties();
			is = this.getClass().getResourceAsStream("/sample.properties");
			prop.load(is);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	public Set<Object> getAllKeys(){
		Set<Object> keys = prop.keySet();
		return keys;
	}
	
	public String getPropertyValue(String key){
		return this.prop.getProperty(key);
	}
	
	public static void main(String a[]){
		
		MyPropAllKeys mpc = new MyPropAllKeys();
		Set<Object> keys = mpc.getAllKeys();
		for(Object k:keys){
			String key = (String)k;
			System.out.println(key+": "+mpc.getPropertyValue(key));
		}
	}
}

sample.properties
db.host=appdomain.java2novice.com
db.user=java2novice
db.password=mypassword
db.service=orcl

Output:
db.password: mypassword
db.user: java2novice
db.host: appdomain.java2novice.com
db.service: orcl
<< Previous Program | Next Program >>

List of Properties class sample programs:

  1. How to load Properties file from a file system?
  2. How to load Properties file from the classpath?
  3. How to load Properties file from a static block or static method?
  4. How to assign default values for unavailable keys in properties file?
  5. How to get all keys from properties file?
  6. How to create and store property file dynamically?
  7. How to store property file as xml file?
  8. How to load property file using class name in java?
Knowledge Centre
ServletOuptputStream Vs PrintWriter
ServletOutputStream: ServletResponse.getOutputStream() returns a ServletOutputStream suitable for writing binary data in the response. The servlet container does not encode the binary data, it sends the raw data as it is.

PrintWriter: ServletResponse.getWriter() returns PrintWriter object which sends character text to the client. The PrintWriter uses the character encoding returned by getCharacterEncoding(). If the response's character encoding has not been specified then it does default character encoding.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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