Ng Sharma

Mikalai Zaikin wrote:

Ng Sharma wrote:if I'm using a ServiceLoader in our program. when mandatory to used 'uses' keyword in module.

When you define service client module you must use "uses" directive, see more details in my guide here:

http://java.boot.by/ocpjd11-upgrade-guide/ch02.html

As well (optionally):

http://java.boot.by/ocpjd11-upgrade-guide/ch02s02.html

First of follow Thanks to provide good stuff.

Cloud you tell me please . how to work ServiceLoader.

if I'm using a ServiceLoader in our program. when mandatory to used 'uses' keyword in module.

please anyone explain me module descriptor file allowed import Why?
what is the used of import statement in module descriptor.

import java.util.*; module superman { }

Here's how you compile and run your application:
javac -module-source-path src -d out -m calc java -p out -m calc/com.ngsharma.oca.Calculator

javac -d out --module-source-path src -m calc
Run Compile command throws
error: module calc not found in module source path

└── src
   └── calculator
       ├── com
       │   └── ngsharma
       │       └── oca
       │           └── Calculator.java
       └── module-info.java


Calculator.java
package com.ngsharma.oca; public class Calculator {    public static int add(int n1, int n2) {        return n1 + n2;    }        public static void main(String[] args) {        System.out.println(add(20, 40));    } }

module-info.java

module calc { }

Compile this above program

javac -d out/calc-module src/calculator/com/ngsharma/oca/Calculator.java src/calculator/module-info.java //Successfully compiled

.
├── out
│   └── calc-module <--- Directory name changed
│       ├── com
│       │   └── ngsharma
│       │       └── oca
│       │           └── Calculator.class
│       └── module-info.class



Run this above program

java -p out --add-modules calc com.ngsharma.oca.Calculator  // Run Successfully, but only using module declare name 'calc', not using module directory name.

Q1. module-info.java file name should be same as Calculator directory name or not

Compiled this module throw error:
javac -d bin --module-source-path src -m calculator throw error module name calc does not match expected name calculator module calc {

Run this module throw error:
java -p out --add-modules calc-module com.ngsharma.oca.Calculator Error occurred during initialization of boot layer java.lang.module.FindException: Module calc-module not found

interface TestShared {    default String finalize() throws Throwable {        System.out.println("Interface : Finalize");        return "";    }    default Object clone() throws CloneNotSupportedException {        System.out.println("Interface : Clone");        return null;    } } public class Shared implements TestShared {    public static void main(String[] args) throws Throwable {        new Shared().take();    }    private void take() throws Throwable{        finalize();        clone();    } }

this program throw weaker privileges. I Can't understand. Please Suggest me. where is my mistake.

See this.

String lang1 = "java"; String lang2 = "java";

lang1 and lang2 pointing a same reference.
Why s3 is not using a unreference String Object.

Please explain step by step..!

public class Test {     public static void main(String[] args) {        String s1 = "Superman";        String s2 = "Superman" + "";                System.out.println(s1 == s2 ); // this statement print: true                String s3 = "";        String s4 = "Supermna" + s3;        System.out.println(s1 == s4); // this statement print : false Why..?   }   }

Best Answer.

https://stackoverflow.com/questions/4343202/difference-between-super-t-and-extends-t-in-java

Explain this statement

System.out.println(true?false:true == true?false:true);

this code segment return a false, Why return a false.

Stephan van Hulst wrote:Neither of your two cases should work, because you're declaring both the variables tf2 and tf4 twice.

typo mistake sorry.

import java.util.*; public class TestFrameWork<T> {    private T first;    private T second;    public TestFrameWork(T first, T second) {        this.first = first;        this.second = second;    }    public List<String> stringList() {        return Arrays.asList(String.valueOf(first),String.valueOf(second));    }    public static void main(String[] args) {         //case : 1     TestFrameWork<Object> tf2 = new TestFrameWork<Object>(23, "Superman");        for (String tf2 : stringList()) {            System.out.println(val);        }           //case : 2        TestFrameWork tf4 = new TestFrameWork(23, "Darkseid");        for (String tf4 : stringList()) { <---- this line generated compile-time error incompatible Type.            System.out.println(val);        }   } }

Case:2 internal Object Type but did not work. why and how..?
please can you solved this problem and explain it.