Packaging & Tool Classes

I. PACKING class

It is the form of encapsulating a basic data type into a class.

1. Common

(1) Long, (2) Integer, (3) Double, (4) Float, (5) Boolean: String In addition to true (case-insensitive), it goes to false.

2. Provide a type conversion method

(1) Example method (2) static method: Parselong ().

Two. Tool class

1.Math Math Tool Class

(1) rounding round;

(2) Upper value ceil (): the smallest integer greater than or equal to it;

(3) lower value floor (): The largest integer less than or equal to it;

(4) random number (): Random number between 0~1.

2.Random Random Number

(1) The seed of random numbers can be passed in the construction method;

(2) A sequence of pseudo-random numbers calculated from the seed of a random number;

(3) Nextint (maximum value);

(4) The default random number seed is the time value.

Packaging Implementation Method:

1  PackageOrg.hanqi.array;2 3 ImportJava.util.Random;4 5  Public classBaozhuang {6 7      Public Static voidMain (string[] args) {8         9         Ten         //Packing class OneLong l=NewLong (100); A          -         //turn a string into a numeric value -Long l1=NewLong ("1000"); the          -String str =1000+ ""; -          -         //turn from wrapper class to basic data type +         LongL2=L1.longvalue (); -  +System.out.println ("l2=" +L2); A  at         LongL3=long.parselong ("1200"); -          -          -         //int -Integer i=NewInteger ("100"); -          inInteger.parseint ("100"); -          to         //float +Float f=NewFloat ("123.45"); -          theFloat.parsefloat ("123.45"); *          $         //DoublePanax NotoginsengDouble d=NewDouble ("12345.67"); -          theDouble.parsedouble ("12345.67"); +          A         //Boolean theBoolean b=NewBoolean ("true"); +          - System.out.println (B.booleanvalue ()); $          $          -          -         //Math Tool Class the          - System.out.println (Math.PI);Wuyi          the         //Rounding -System.out.println (Math.Round (1234.56789)); Wu          -         Doublede=1234.56; About          $         //Keep 2 digits after the decimal point -System.out.println (Math.Round (de*100)/100.0); -          -         //The number after the decimal point. A          +         //Lower Value: The largest integer less than or equal to it the System.out.println (Math.floor (DE)); -          $         //Upper Value: The smallest integer greater than or equal to it the System.out.println (Math.ceil (DE)); the          the          the         //between random number 0~1 -          in System.out.println (Math.random ()); the System.out.println (Math.random ()); the System.out.println (Math.random ()); About System.out.println (Math.random ()); the System.out.println (Math.random ()); the System.out.println (Math.random ()); the System.out.println (Math.random ()); +          - System.out.println (); the         BayiRandom r=NewRandom (); the          the         //random number seed -         //pseudo-Random number -         //based on the seed. the         //the generation sequence of random numbers determined by the seed the         //r=new Random (ten); the          the          for(intm=0;m<10;m++) -         { theSystem.out.println (R.nextint (30)); the         } the         94     } the}

Baozhuang

Packaging & Tool Classes