Return Array From Method

  public class ReturnArrayFromMethod {
  
  public static double[] doubleArray(double []array){
    
     double newmarks[] = new double[array.length];
     
     for (int i=0;i<array.length;i++)
       newmarks[i] = array[i] * 2;
     
     return newmarks;
    } //end printArray
  
    public static void printArray(double []array){
      for (int i=0;i<array.length;i++)
        System.out.println(array[i]);
  } //end printArray

  public static void main(String[] args) {
    
    double marks[] = {45.5,46,49,13};
    double marks2[] = doubleArray(marks);
    
    printArray(marks);
    System.out.println("========");
    printArray(marks2);
    
  }//end main
  
} //end class

PassArray To Method , Pass By Value

  public class PassArrayToMethodExample {
  
  public static void doubleInt(int num){
    num= num*2;
    System.out.println(num);
  }
  
  public static void doubleArray(int []array){
  for (int i=0;i<array.length;i++)
    array[i] = array[i] * 2;
 } //end printArray


 public static void printArray(int []array){
   for (int i=0;i<array.length;i++)
     System.out.println(array[i]);
 } //end printArray


  
  public static void main(String[] args) {
   int num = 5;

   doubleInt(num);
   System.out.println(num);

   int a[] = {5,10,20,30,40};
   int b[] = {15,2,330,40};
   int c[] = {40};
   int d[] = {5,50,320,40,40,100,200,300,400};
   
   doubleArray(a);
   printArray(a);

 } //end main


}//end class

Create JButton Array Example

import javax.swing.*;
import java.awt.*; // layout


public class JButtonArrayExample extends JFrame{
  
  private JButton btn[] = new JButton[20];
  
  public JButtonArrayExample(){
    
    for (int i=0; i <btn.length;i++){
      btn[i] = new JButton("Button "+ i);
      getContentPane().add(btn[i]);
    }     
     getContentPane().setLayout(new FlowLayout());
     
  }
  
  public static void main(String[] args) {
    JButtonArrayExample e = new JButtonArrayExample();
    e.setSize(300,300);
    e.setVisible(true);
  } //end main
  
}//end class

Practical 10 Question 1

import javax.swing.*;
class p10q1 {
  public static void main(String[] args) {
    int[] intArray = {11,0,10,2,2};
    int highest = 0;
    String output = "";
    
    for (int i=0; i<intArray.length;i++){
      
      if (intArray[i]>highest)
        highest = intArray[i];//11
      
      if (i!= intArray.length-1) //if it is not the last element
        output += intArray[i] + ","; 
      else
        output += intArray[i]; //don't put comma
     
    } //end for
    
    // TODO: Use JOptionPane to show results : 1 line
    // Hint: use output + highest
    JOptionPane.showMessageDialog(null,
                                  "Elements: " + output+
                                  "\nHighest: " + highest);
    
    
  }//end main
}//end class

3 Different Ways of Declaring, Creating and Initialising an Array

public class ArrayExample2 {
public static void main(String[] args) {

// Step 1: Declare
// Step 2: Create the array
// Step 3: Initialise

// Step 1
double temp0[];

// Steps1 +2
double temp1[] = new double[7];

// Step 3: initialising
temp1[0] = 37.5;
temp1[1] = 38.5;

// 3-in-1 method
// Declare,
double temp2[] = {37.5, 38.5, 39.5, 40.5,41.5};

System.out.println(temp2[2]);

// Retrieve the length of an array
System.out.println(temp2.length);

for (int i=0;i<temp2.length;i++){
System.out.println(temp2[i]);
}//end for



} //end main
} //end class

Calc. Average temperature example

public class CompleteTemperatureExample {
public static void main(String[] args) {

double []temp1 = new double[7];
double temp2[] = {39.0,39.5, 26, 28};


double total=0;

for (int i=0;i<temp2.length;i++){
total+=temp2[i];
} //end for

System.out.println("Average is" + total/temp2.length);

} //end main
} //end class

Demo Default Values of Primitive + Object

  public static void main(String args[]) {
    
    double []temperatures;
    int numstudents[] = new int[5];
    boolean hungry[] = new boolean[10];
    char []grades = new char[3];
    String names[] = new String[8];
    
    // Retrieve second value
    System.out.println("String:" + names[1]);
    
    // Retrieve second value
    System.out.println("char:" + grades[1]);
    
    // Retrieve second value
    System.out.println("boolean:" + hungry[1]);
    
    // Retrieve second value
    System.out.println("int:" + numstudents[1]);
    
    // Allocate space to store 7 double values
    temperatures = new double[7];
    // Retrieve second value
    System.out.println(temperatures[1]);
    
  } //end main