java - Advantages of Constructor Overloading -

-

i new java , trying learn subject, having previous programming exposure in html/css. have started herbert schildt , progressed through few pages.

i unable understand exact advantages of constructor overloading. isn't easier overload methods using single constructor flexibility? if trying use constructor overloading use 1 object initialize another, there simpler ways it! benefits , in situation should use constructor overloading.

constructor overloading useful simulate default values, or construct object existing instance (copy)
here example: 

public class color {      public int  r, g, b, a;      // base ctr     public color(int r, int g, int b, int a) {         this.r = r;         this.g = g;         this.b = b;         this.a = a;     }      // base, default alpha=255 (opaque)      public color(int r, int g, int b) {         this(r, g, b, 255);     }      // ctr double values     public color(double r, double g, double b, double a) {         this((int) (r * 255), (int) (g * 255), (int) (b * 255), (int) (a * 255));     }      // copy ctr     public color(color c) {         this(c.r, c.g, c.b, c.a);     }  }

here, first constructor simple. specify r,g,b & alpha value color.

while enough use color class, provide second constructor, liter, auto assign 255 alpha if not specified user.

the third ctr shows can instantiate color object double between 0. , 1. instead of integers.

the last 1 takes color unique argument, copies given object.

the benefits lies in fact first constructor called, , can use manually count instances. let have private static int count=0 attribute, can track number of color instance this:

    // base ctr     public color(int r, int g, int b, int a) {         this.r = r;         this.g = g;         this.b = b;         this.a = a;         ++count;     }

countis incremented constructor.


Comments

Post a Comment

Popular posts from this blog

c++ - Linked List error when inserting for the last time -

-
so have part of code here this loop 5 times (max = 5) insert word link list. for ( int = 0 ; < max ; i++ ) { string alphabet = g->returnalphabets(); l[i]->addwords(alphabet[i]); } and have insert word part here string line; fstream myfile ("words.txt"); while (!myfile.eof()) { getline(myfile,line); if ( alphabet == line[0] ) { listnode *newnode = new listnode; if ( head == null ) { newnode->item = alphabet; newnode->next = null; head = newnode; } else { newnode->item = line; prev = cur; prev->next = newnode; } cur = newnode; } } myfile.close(); my problem gives me error on last loop. meaning on max = 4, insert node. rest of loop fine. when decrease max 4 meaning loop 4 times, program error-free when program loops 5 times gives error. anyone can poin...
Read more

java - activate/deactivate sonar maven plugin by profile? -

-
i use sonar plugin executes if activated in maven profile. sonar runs on every compile. the problem build fail other team members not have sonar application installed locally. pom.xml checked in team members same copy including sonar configuration, don't want them modify purpose of disabling sonar (they might inadvertently check modified copy in). please advise how configure maven (.m2/settings.xml) and/or pom.xml sonar feature can enabled/disabled local profile. here sonar configuration in each project's pom.xml: <plugin> <groupid>org.codehaus.mojo</groupid> <artifactid>sonar-maven-plugin</artifactid> <version>1.0</version> <executions> <execution> <id>make-sonar</id> <phase>compile</phase> <goals> <goal>sonar</goal> </goals> </execution> </executions> ...
Read more

java - What is the difference between String. and String.this. ? -

-
this question has answer here: meaning of .this , .class in java 2 answers i'll straight point. im still learning bit of syntax , want know difference between code is code a: public class buttonz extends jbutton{ public buttonz(){ settext(new string(string.valueof(i))); } } please ignore fact i undeclared, not lost. code b: public class buttonz extends jbutton{ public buttonz(){ settext(new string(string.this.charat(i))); } } what don't yet understand difference in typing string.this , string. i under assumption when use dot operator on class accessing it's static methods(and/or variables if they're not hidden). i have studied little bit , have concluded when using string. accessing string static methods.. when using string.this. i'm accessing methods class buttonz extendi...
Read more