Java Fundamentals (long-term updates)

Want to record the basic knowledge of Java, if you encounter a miscellaneous problem, also add to here, no longer another new blog

1. Shift operation (<<, >>)

 Public Static void Main (string[] args) {        int a = 8;         // 8<<3--8 * (2 of 3 times)        System.out.println ("8<<3----->" + (8<<3));         // 8>>3--8/(2 of 3 times)        System.out.println ("8>>3----->" + (8>>3));            }

8<<3----->648>>3----->1

The shift operation is the fastest in the computer.

Take 11 as an example

11 binary corresponding is 1011

11<<3 Move right 3-bit to get 1011--and decimal 88 "11* (2 of 3)"

11>>3 move left 3-bit to get 1--and decimal 1 "11/(2 3)"

Put on the code to verify it.

 Public Static void Main (string[] args) {         int a = one;                  System.out.println (Integer.tobinarystring (a));                  System.out.println (Integer.tobinarystring (a<<3) + "decimal:" + (a<<3));                  System.out.println (Integer.tobinarystring (a>>3) + "decimal:" + (a>>3));            }

101,110,110,000 binary: 8,810 binary: 1

　　

2. Bitwise non-operator (~)

 Public Static void Main (string[] args) {        int A =-9;         int b = 9;         int c = 0;         // ~a--(-a-1)        System.out.println ("~a---->" + (~a));        System.out.println ("~b---->" + (~b));        System.out.println ("~c---->" + (~c));                }

~a---->8~b---->-10~c---->-1

Java Fundamentals (long-term updates)