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1. The this keyword is used only for those special cases where you must explicitly use the reference to the current object.
code example: https://github.com/wangbingfeng/OnJava8-Examples/blob/master/housekeeping/Leaf.java
2. The this keyword is useful for passing the current object to another method.
code example: https://github.com/wangbingfeng/OnJava8-Examples/blob/master/housekeeping/PassingThis.java
3. Calling Constructors from Constructors use this keyword.
pay attention to the comments about this keyword in below code.
// housekeeping/Flower.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Calling constructors with "this"
public class Flower {
int petalCount = 0;
String s = "initial value";
Flower(int petals) {
petalCount = petals;
System.out.println("Constructor w/ int arg only, petalCount= " + petalCount);
}
Flower(String ss) {
System.out.println("Constructor w/ String arg only, s = " + ss);
s = ss;
}
Flower(String s, int petals) {
this(petals);
// - this(s); // Can't call two!
this.s = s; // Another use of "this"
System.out.println("String & int args");
}
Flower() {
this("hi", 47);
System.out.println("no-arg constructor");
}
void printPetalCount() {
// - this(11); // Not inside non-constructor!
System.out.println("petalCount = " + petalCount + " s = " + s);
}
public static void main(String[] args) {
Flower x = new Flower();
x.printPetalCount();
}
}
/* Output:
Constructor w/ int arg only, petalCount= 47
String & int args
no-arg constructor
petalCount = 47 s = hi
*/