count=count++

// count=count++;
// step 1: JVM copy count value to temp 
// step 2: count incremented by 1
// step 3: assign temp to count, count reset to 0

public class SelfIncrementTest {
   
    public static void main(String[] args){
       
        int count = 0;
        for (int i=0;i<10;i++){
            count = count++;
        }
       
        System.out.println(count);
    }

}
OUTPUT
0

varargs

public class VarargsTest {
   
    public void methodA(String str, Integer... is){
       
        System.out.println("first methodA called");
       
    }
   
    public void methodA(String str, String... strs){
        System.out.println("second methodA called");
       
    }
   
    public static void main(String[] args){
       
        VarargsTest vt = new VarargsTest();
        vt.methodA("USA", 0);
        vt.methodA("USA",  "People");
        //vt.methodA("USA"); // compile error. compiler does not know which methodA to invoke
        //vt.methodA("USA",  null); // compile error. null is not any type. compiler does not know which methodA to invoke
       
       
    }

}



OUTPUT
first methodA called
second methodA called

Ternary type must match

// data types in ternary must match

public class TernaryTest {
   
    public static void main(String[] args){
        int i = 80;
        String s1 = String.valueOf(i<90?90:100);
        String s2 = String.valueOf(i<90?90:100.0); // 90 converted to 90.0
       
        System.out.println("s1="+s1);
        System.out.println("s2="+s2);
    }

}

OUTPUT
s1=90
s2=90.0

instanceof

import java.util.Date;

public class InstanceOfTest {
  
    // if no extend or implementation relationship between two objects, it will give compile error.
  
    public static void main(String[] args){
        boolean b = false;
      
        b = "a" instanceof String;
        System.out.println(b);
      
        b = new String() instanceof String;
        System.out.println(b);
      
        b = new Object() instanceof String; // object is not instanceof String
        System.out.println(b);
      
        //b = 'A' instanceof Character;
        // compile error. 'A' is simple variable and Character is object
      
        b = null instanceof String; // null is not instanceof any types
        System.out.println(b);
      
      
        String s = (String) null; // s is still null even after conversion
        System.out.println(s);
      
        b = (String) null instanceof String; // null is still null even after conversion
        System.out.println(b);
      
        //b = new Date() instanceof String;
        // compile error.
        // No extend or implementation relationship between Date and String so compile error.
    }

}



OUTPUT
true
true
false
false
null
false