Sudar Shan

I think I have now understood a bit; .getName() works on an instance of a Class and .class works on the Class name itself. So, I am assuming that ".class" is similar to a static method.

Since the example I had posted is not actually instantiating the class but only wants to get the class name, .class has been used. (right?)

package com.company; public class Main { public static void main(String[] args) { Dummy newDummy = new Dummy() ; System.out.println(newDummy.getClass()); System.out.println(Dummy.class); } } class Dummy { public String toString(){ return "1"; } }

Thank you Henry for the response and also for fixing my code tag.

Does that mean that .getName() and .class give the same result (except for primitive type where .getName doesn't work)?

I am looking at the following mapreduce example and don't understand what does the word count.class signify in the main method. What is the .class for?
public class WordCount { public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable>{ private final static IntWritable one = new IntWritable(1); private Text word = new Text(); public void map(Object key, Text value, Context context ) throws IOException, InterruptedException { StringTokenizer itr = new StringTokenizer(value.toString()); while (itr.hasMoreTokens()) { word.set(itr.nextToken()); context.write(word, one); } } } public static class IntSumReducer extends Reducer<Text,IntWritable,Text,IntWritable> { private IntWritable result = new IntWritable(); public void reduce(Text key, Iterable<IntWritable> values, Context context ) throws IOException, InterruptedException { int sum = 0; for (IntWritable val : values) { sum += val.get(); } result.set(sum); context.write(key, result); } } public static void main(String[] args) throws Exception { Configuration conf = new Configuration(); Job job = Job.getInstance(conf, "word count"); job.setJarByClass(WordCount.class); job.setMapperClass(TokenizerMapper.class); job.setCombinerClass(IntSumReducer.class); job.setReducerClass(IntSumReducer.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); FileInputFormat.addInputPath(job, new Path(args[0])); FileOutputFormat.setOutputPath(job, new Path(args[1])); System.exit(job.waitForCompletion(true) ? 0 : 1); } }

yes but a quiz! And grant a cow for someone who answers all questions on it! ...nah, I am digressing. Its ok. Good day guys.

thank you all for your answers. I will be more careful when I post the next time.

BTW, I think there should be a quiz on HowToAskQuestions.. for new forum members ;)

apologies Pawel, I will try to provide more information next time. And as you said, I am missing the override to toString method.

I would also like to know why no argument constructor is bad.

public class Main { public static void main(String[] args) { Employee[] newEmployee = new Employee[10] ; newEmployee[0] = new Employee("SXR"); System.out.println(newEmployee[0]); } } class Employee { int empID = 0; private static int lastEmpID = 0; String empName; Employee(String newEmpNam) { lastEmpID = lastEmpID + 1; empID = lastEmpID; empName = newEmpNam; } public String toString(){ return empID + ":" + empName ; } }

No, the code did not compile. However, when I declared the array as "Employee[] newEmployee = null", I got it compiled but it threw the run time error.

I have been coding in IBM i for 8+ years (COBOL and RPG ). Java is very new to me, please excuse if I ask way too basic questions. I believe in writing silly programs like these. This makes me understand the concepts and to be able to identify the issue if it were to occur again (though you guys might facepalm)

I have removed the no argument constructor, something isn't right yet:
public class Main { public static void main(String[] args) { Employee[] newEmployee = new Employee[10] ; newEmployee[0] = new Employee("SXR"); System.out.println(newEmployee[0]); } } class Employee{ int empID = 0; private static int lastEmpID=0; String empName ; Employee(String newEmpNam) { lastEmpID = lastEmpID + 1 ; empID = lastEmpID ; empName = newEmpNam ; }

Hi ,

I am not sure if I have grasped the object concept well enough.

I am trying to create a Generic Object Streamer Class to test my understanding on 1) Generic Classes 2) ObjectOutputStream.

I have seen few discussions on objects needing to be initialized. But I don't understand why, or whats happening behind the scenes in terms of memory/pointer.

public class Main { public static void main(String[] args) { Employee[] newEmployee; newEmployee[0] = new Employee("SXR"); } } class Employee{ int empID = 0; private static int lastEmpID=0; String empName ; Employee() {} Employee(String newEmpNam) { lastEmpID = lastEmpID + 1 ; empID = lastEmpID ; empName = newEmpNam ; } } Edit : The code doesn't have anything about generics at this time. I eventually plan to do that..

Hi forum members,

I found this forum very friendly and thought I will join here. Here I am, after several attempts to get myself a display name.

I am new to Java programming. My motivation to learn java is to move towards big data. I have been programming for about 8 years in IBM iSeries, that means that I don't have object oriented programming experience. And I did not study programming at my college.

I have googled about the need for Java to dive into big data and I have started learning Java. But I prefer to do a mock Java project that would encompass important concepts. Can someone guide me, or assign me a mock project.

Thank you.