added notes for java data type

amir1422 · amir1422 · commit 0893909fa6ef · 2022-07-20T15:14:56.000+05:30
diff --git a/README.md b/README.md
@@ -324,6 +324,40 @@ Joda Date api
 			2022-04-27T16:53:23.903014+05:30[Asia/Calcutta]
 			Wed Apr 27 16:53:23 IST 2022
 
-		
-		
-		
+
+
+
+
+
+##java Data Type deep concept
+   ----------------------------------------------
+      java contain 8 data type(primitives)
+      6 type number - 6(byte-1Byte,short-2Byte,int-4Byte,long-8Byte,float-4Byte,double-8Byte)
+      1 type for boolean (boolean-1bit) [0,1]
+      1 type for character(char-2byte) --only positive num[0-(2^16-1)] = [0 to 65535]
+       for byte -contains both negative & positive -- so in 1 byte = 8 bits
+       total possible number using 8 bit = 2^8 = 256 means half number should be negative and half number should be positive
+       first negative number; 256/2 = -128
+      last postive number = 256 -(128+1) = 127
+      so validate range [-128,127]
+      formula = total possible = (last-first+1)  = 256 = 127-(-128)+1=256
+      1 added because zero belongs to positive number
+      note: always java store negative num inform of 2's complement.
+      
+              //2s complement rules => reverse all bit from left to right plus
+              change all zero to 1 from left to right till 1st one
+              example:
+              num =-5 =  binary for 5 = 00000101
+              apply 2s complement rules = 11111011 (java store for -5)
+      
+      
+      
+           */
+          public static void main(String[] args) {
+              byte num = -5;  // binary 1 = 00000001 =>1s complement = 11111110 =2's compl =11111110
+              String s = Integer.toBinaryString(num);
+              System.out.println(s.substring(24));
+              
+          }
+      
+      
diff --git a/src/main/java/com/amir/java/type/JavaTypeDemo.java b/src/main/java/com/amir/java/type/JavaTypeDemo.java
@@ -0,0 +1,33 @@
+package com.amir.java.type;
+
+public class JavaTypeDemo {
+    /*
+    java contain 8 data type(primitives)
+   6 type number - 6(byte-1Byte,short-2Byte,int-4Byte,long-8Byte,float-4Byte,double-8Byte)
+   1 type for boolean (boolean-1bit) [0,1]
+   1 type for character(char-2byte) --only positive num[0-(2^16-1)] = [0 to 65535]
+       // for byte -contains both negative & positive -- so in 1 byte = 8 bits
+        // total possible number using 8 bit = 2^8 = 256 means half number should be negative and half number should be positive
+        // first negative number; 256/2 = -128
+        // last postive number = 256 -(128+1) = 127
+        // so validate range [-128,127]
+        // formula = total possible = (last-first+1)  = 256 = 127-(-128)+1=256
+        //1 added because zero belongs to positive number
+        note: always java store negative num inform of 2's complement.
+
+        //2s complement rules => reverse all bit from left to right plus
+        change all zero to 1 from left to right till 1st one
+        example:
+        num =-5 =  binary for 5 = 00000101
+        apply 2s complement rules = 11111011 (java store for -5)
+
+
+
+     */
+    public static void main(String[] args) {
+        byte num = -5;  // binary 1 = 00000001 =>1s complement = 11111110 =2's compl =11111110
+        String s = Integer.toBinaryString(num);
+        System.out.println(s.substring(24));
+
+    }
+}
