Java HariKrishna

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interrupt() method terst case program
=========================
class MyThread13 extends Thread {

public void run() {

System.out.println("run start");
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
System.out.println("IE raised");
}
System.out.println("run end");
}
}
public class Test23 {
public static void main(String[] args) throws InterruptedException {
System.out.println("main start");

MyThread13 mt = new MyThread13();
mt.interrupt();

mt.start();
//mt.interrupt();

Thread.sleep(2000);

//mt.interrupt();

System.out.println("main end");
}
}

What is import and why import?
- The import is a keyword. It is used for accessing
one packgaed classes from other packaged classes

How many ways we can access one pakcaged class from other packaged class?
- To access one packaged classes from other packaged classes we have two approaches
1) by using fully qualified name
2) import statement

- If two classes are belongs the either default package or belongs to same package
for accessig one class from other class we no need to use FQN or we no need to use
import statement we can directly access this calss by usign its name

- We must use FQN or import statement only if the classes are belongs to different packages

Case #1: classes are belongs default package
- we no need to use FQN or import statement
- we can access class A from class Test directly by its name
//A.java
class A {
static void m1(){
System.out.println("A m1");
}

void m2(){
System.out.println("A m2");
}
}

//Test.java
class Test {
public static void main(String[] args){
A.m1();

A a1 = new A();
a1.m2();
}
}

Case #2: classes are belongs to same package p1
- we no need to use FQN or import statement
- we can access class A from class Test directly by its name

//A.java
package p1; Case #2: both java file in CWD
class A { - we won't get AC
static void m1(){ - we must compile first A.java separately
System.out.println("A m1"); >javac -d . Test.java
} CE: can not find symbol class A
>javac -d . A.java
void m2(){ p1
System.out.println("A m2"); A.class
} >javac -d . Test.java
} p1
A.class
//Test.java Test.class
package p1; >java p1.Test
class Test { A m1
public static void main(String[] args){ A m2
A.m1(); - For achieving AC, we must place class A in package p1 folder

A a1 = new A(); Case #2.1: placing A.java file in package p1 folder
a1.m2(); |- Test.java
|- p1
A.java
} >javac -d . Test.java
} |- p1
|- A.class
|- Test.class
>java p1.Test
A m1
A m2

- There is not promble in placing Test.java file outside packge folder p1
- it is not recommanded to save package java file outside packaed folder
- If we place Test.java file inside packaged folder compilation process is
changed, we mut not use -d option, but we must use p1\Test.java
becuase package folder is already available

Case #2.2: placing Test.java file in package p1 folder
|- p1
|- A.java
|- Test.java

>javac p1\Test.java
|- p1
|- A.java
|- Test.java
|- A.class
|- Test.class

>java p1.Test
A m1
A m2


Case #3: classes are belongs to different packages

//A.java
package p1;
class A {
static void m1(){
System.out.println("A m1");
}

void m2(){
System.out.println("A m2");
}
}

//Test.java
package p2;
class Test {
public static void main(String[] args){
A.m1();

A a1 = new A();
a1.m2();

}
}

======================================
//Test.java
package p2;
class Test {
public static void main(String[] args){
p1.A.m1();

p1.A a1 = new p1.A();
a1.m2();

}
}

=====================================
//A.java
package p1;
public class A {
static void m1(){
System.out.println("A m1");
}

void m2(){
System.out.println("A m2");
}
}
=====================================
//A.java
package p1;
public class A {
public static void m1(){
System.out.println("A m1");
}

public void m2(){
System.out.println("A m2");
}
}