Methods in Java

Author: kishanrajput23

31.Methods/README.md

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+# Java Tutorial: Methods in Java
+- Sometimes our program grows in size, and we want to separate the logic of the main method from the other methods.
+- For instance, if we calculate the average of a number pair 5 times, we can use methods to avoid repeating the logic. [DRY – Don’t Repeat Yourself]
+
+### Syntax of a Method
+- A method is a function written inside a class. Since Java is an object-oriented language, we need to write the method inside some class.
+- Syntax of a method : 
+```
+returnType nameOfMethod() {
+//Method body
+}
+```
+- The following method returns the sum of two numbers
+```
+int mySum(int a, int b) {
+	int c = a+b;
+	return c;	//Return value
+}
+```
+
+- In the above method, int is the return data type of the mySum function.
+- mySum takes two parameters: int a and int b.
+- The sum of two values integer values(a and b) is stored in another integer value named 'c'.
+- mySum returns c.
+
+### Calling a Method : 
+- A method can be called by creating an object of the class in which the method exists followed by the method call:
+```
+Calc obj = new Calc(); //Object Creation
+
+obj.mySum(a , b); //Method call upon an object
+```
+- The values from the method call (a and b) are copied to the a and b of the function mySum. Thus even if we modify the values a and b inside the method, the values in the main method will not change.
+
+### Void return type : 
+- When we don’t want our method to return anything, we use void as the return type.
+
+### Static keyword : 
+- The static keyword is used to associate a method of a given class with the class rather than the object.
+- You can call a static method without creating an instance of the class.
+- In Java, the main() method is static, so that JVM can call the main() method directly without allocating any extra memory for object creation. 
+- All the objects share the static method in a class.
+
+### Process of method invocation in Java : 
+- Consider the method Sum of the calculate class as given in the below code :
+
+```
+class calculate{
+     int sum(int a,int b){
+        return a+b;
+    }
+```
+
+- The method is called like this:
+
+```
+class calculate{
+     int sum(int a,int b){
+        return a+b;
+    }
+
+public static void main(String[] args) {
+         
+        calculate obj = new calculate();
+        int c = obj.sum(5,4);
+        System.out.println(c);
+    }
+}
+```
+```
+Output : 9
+```
+- Inside the main() method, we've created an object of the calculate class.
+- obj is the name of the calculate class.
+- Then, we've invoked the sum method and passed 5 and 4 as arguments.
+
+**Note:** In the case of Arrays, the reference is passed. The same is the case for object passing to methods.
+
+### Code as described in the video:
+```
+package com.company;
+
+public class cwh_31_methods {
+
+    static int logic(int x, int y){
+        int z;
+        if(x>y){
+            z = x+y;
+        }
+        else {
+            z = (x +y) * 5;
+        }
+        x = 566;
+        return z;
+    }
+
+
+    public static void main(String[] args) {
+        int a = 5;
+        int b = 7;
+        int c;
+        // Method invocation using Object creation
+        //cwh_31_methods obj = new cwh_31_methods();
+        //c = obj.logic(a, b);
+        c = logic(a, b);
+        System.out.println(a + " "+ b);
+        int a1 = 2;
+        int b1 = 1;
+        int c1;
+        c1 = logic(a1, b1);
+        System.out.println(c);
+        System.out.println(c1);
+    }
+}
+```
+
+**Handwritten Notes: [Click to Download](https://api.codewithharry.com/media/videoSeriesFiles/courseFiles/java-tutorials-for-beginners-31/Ch7.pdf)**
+
+**Ultimate Java Cheatsheet: [Click To Download](https://api.codewithharry.com/media/videoSeriesFiles/courseFiles/java-tutorials-for-beginners-31/UltimateJavaCheatSheet.pdf)**