Java Novice Note 10 builder

1. Small program of Draw award

Package Com.yfs.javase;import Java.io.ioexception;import Java.nio.charbuffer;import Java.util.random;public class DEMO1 {/** * Analog draw award */public static void Main (string[] args) {random ran = new Random (); int[] A = new int[7];  System.out.println ("Start of the draw:");//Generate award for (int i = 0; i < a.length; i++) {A[i] = Ran.nextint (33) + 1;//Find duplicates for (int j = 0; J < I; J + +) {if (a[j] = = A[i]) {System.out.println ("+" + (i + 1) + "bit" + a[j] + "+" + (j + 1) + "number Same");    i--;//to repeat the number of}}}system.out.println ("The result of this draw:");//Output award for (int i = 0; i < a.length; i++) {System.out.print (a[i] + "\ t");}}

2. Constructors

Package Com.yfs.javase;public class Constructiondemo {public int b = 10;/** * Construction method * 1. If the class does not provide a constructor method  * Compile-time system to automatically add an argument-free construction method  * 2. Constructor method to instantiate object  * 3. Class declaration Construction method The system no longer provides a constructor method * 4. No return value type declaration has the same name as the class * 5. The form of the instantiated object is determined by the construction method */public Constructiondemo () {Syst Em.out.println ("Create an Object");}    Constructor method overloads public Constructiondemo (String msg) {System.out.println ("constructor with arguments   " +  msg);} Public Constructiondemo (Double A, int[] b) {System.out.println ("construction method with 2 parameters   " +  a);//execute output for (int i = 0; i < B.L Ength; i++) {System.out.println (b[i]);}} Common method public void Constructiondemo () {System.out.println ("method with return value ...) Whether to create an object "); public static void Main (string[] args) {Constructiondemo cs = new Constructiondemo ();//Call construction method}public void Test (int a) {Sy STEM.OUT.PRINTLN ("Call Test () ....");}}

3. Constructor test

Package Com.yfs.javase;public class ConTest {public static void main (string[] args) {Constructiondemo  CSD = new Constr Uctiondemo ();        Csd.test (a);        Call the constructor method with parameters to instantiate the object        constructiondemo  c1 = new Constructiondemo ("Hello everyone! ");                        Constructiondemo  c2 = new Constructiondemo (a);        Constructiondemo  c2 = new Constructiondemo (new int[]{1,2,3});}}

4.Person class

The package com.yfs.javase;//constructs a method using this to call public class Person {String name;int age;char sex;boolean married;public person ( {System.out.println ("Create person object"); speak ();//Call other methods}public person (String N) {//person ();//this ();/ This invokes the constructor method without arguments this ("Harry", 25, ' female ', true);//must be the first sentence of the construction method code System.out.println ("Call person (name) ...");} The constructor initializes the property to the public person (String N, int A, char s, boolean m) {name = n;//the passed-in parameter is assigned to the attribute age  = A;sex = s;married = m; System.out.println ("Person (String N, int A, char s, boolean m)");} public void Speak () {System.out.println (name + "Are you human?") ");} public void Sleep () {System.out.println (name +) did you sleep? Speak ();//Call other methods//person ();//Other methods cannot call construction method}}

Class 5.Person Test 1

Package Com.yfs.javase;public class Persontest {public static void main (string[] args) {person P1 = new Person ("Zhang San", 20, ' Male ', false); System.out.println (P1.name); System.out.println (P1.age); System.out.println (P1.sex); System.out.println (p1.married);p 1.speak ();p 1.sleep (); person P2 = new Person ();}}

Class 6.Person 2

Package Com.yfs.javase;public class Person {String name;int age;char sex;boolean married;public person () { System.out.println ("Create person Object");} Public person (String name) {//Parameter name has the same name as the property  name local variable this.name = name;//Property This represents the current object System.out.println ("Call person" + Name+ ") ..."); public void Speak () {System.out.println (this.name +) Are you really human? "); System.out.println (this);} public void Sleep () {System.out.println (name +) did you sleep? ");} Destroying an object is the method called @overrideprotected Void Finalize () throws Throwable {System.out.println (name  + "object is destroyed ...");}

7.Person Class 2 Test (garbage collection)

Package Com.yfs.javase;public class PersonTest1 {public static void main (string[] args) {person P1 = new Person ("John Doe");//Object Life from Newp1.speak (); person P2 = new Person ();p 2.speak (); Person P3 = NULL;P3 = new Person ("Zhang San");p 3 = null;//Life End System.GC ();//Forced Recycle System.out.println ("Program execution End ...");}}

Java Novice Note 10 builder