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Java Basics
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Course Content

Java Basics

Java Basics

1. Getting Started
Backend DevelopmentRole of Java in the Backend Java Advantages Memory Types In Java Java's SyntaxYour First ProgramComments
2. Basic Types, Operations
Primitive Data TypesPrimitive Types ChallengeChar and ASCII TableMathematical Operations in JavaIf-Else StatementSwitch-Case StatementWeekday Switch Challenge
3. Loops
Introduction to LoopsWhile-LoopDo-While LoopFor-Loop Increment and DecrementInfinite Loop (bonus)Challenge: Factorial
4. Arrays
What is Array?Using Loops with ArraysIndex Out Of BoundsTwo-Dimentional ArrayIteration In Two-Dimensional ArrayFor-Each Loop
5. String
What Is String? Basic Methods In String Part 1Basic Methods In String Part 2B-Inclusion Filter ChallengeNullPointer Exception StringBuilderString Pool, Method Equals() Summary

bookIteration In Two-Dimensional Array

How to Iterate Inside Two-Dimensional Array Using a for-loop?

Iterating through a two-dimensional array can be a bit challenging to grasp initially, so don't worry if it doesn't click right away. In this chapter, I'll demonstrate how to do it and explain how it functions.

We use a nested loop to iterate through a two-dimensional array, meaning one loop inside another. The outer loop iterates over the rows, while the inner loop iterates over the columns. Let's examine the syntax for iterating through a two-dimensional array using the example array we created in the previous chapter:

java

Main

copy

              
12345678910111213141516

            
package com.example;

public class Main {
    public static void main(String[] args) {
        int[][] twoDimensionalArray = { {1, 2, 3, 4},
                                        {5, 6, 7, 8},
                                        {9, 10, 11, 12},
                                        {13, 14, 15, 16} };
        for (int i = 0; i < twoDimensionalArray.length; i++) {
            for (int j = 0; j < twoDimensionalArray[0].length; j++) {
                System.out.print(twoDimensionalArray[i][j] + " ");
            }
          System.out.println();
        }
    }
}

Let's delve into the meaning of each element in the code snippet provided above:

  • int[][] twoDimensionalArray = - This line initializes a two-dimensional array;
  • for (int i = 0; i < twoDimensionalArray.length; i++) - The first for-loop iterates over the rows of our matrix. While we're on the first row, our program enters the nested loop, which doesn't impact the outer loop. The variable i represents the current row number;
  • for (int j = 0; j < twoDimensionalArray[0].length; j++) - The second for-loop iterates over the columns of the matrix. While we're on the 0th row, we iterate through the columns of that row. The variable j represents the current column number;
  • System.out.print(twoDimensionalArray[i][j] + " "); - In this line, we use System.out.print to display our values in a single line. Let's see how it operates: while we're on the 0th row, we iterate through the columns on that row. For example, array[0][1], followed by array[0][2], and so on. We continue through the columns as long as j is less than array[0].length. Once we reach array[0].length, we return to the outer array and move to the first row. For example, array[0][3] -> array[1][0]. We've reached our boundaries and then transitioned to row 1.
Task
test

Swipe to show code editor

Your task is to locate and display the diagonal (from the top-left corner to the bottom-right corner) of the provided matrix on the screen:

Note

The diagonal represents a line in the matrix where the row and column numbers are identical.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

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Section 4. Chapter 5
toggle bottom row

bookIteration In Two-Dimensional Array

How to Iterate Inside Two-Dimensional Array Using a for-loop?

Iterating through a two-dimensional array can be a bit challenging to grasp initially, so don't worry if it doesn't click right away. In this chapter, I'll demonstrate how to do it and explain how it functions.

We use a nested loop to iterate through a two-dimensional array, meaning one loop inside another. The outer loop iterates over the rows, while the inner loop iterates over the columns. Let's examine the syntax for iterating through a two-dimensional array using the example array we created in the previous chapter:

java

Main

copy

              
12345678910111213141516

            
package com.example;

public class Main {
    public static void main(String[] args) {
        int[][] twoDimensionalArray = { {1, 2, 3, 4},
                                        {5, 6, 7, 8},
                                        {9, 10, 11, 12},
                                        {13, 14, 15, 16} };
        for (int i = 0; i < twoDimensionalArray.length; i++) {
            for (int j = 0; j < twoDimensionalArray[0].length; j++) {
                System.out.print(twoDimensionalArray[i][j] + " ");
            }
          System.out.println();
        }
    }
}

Let's delve into the meaning of each element in the code snippet provided above:

  • int[][] twoDimensionalArray = - This line initializes a two-dimensional array;
  • for (int i = 0; i < twoDimensionalArray.length; i++) - The first for-loop iterates over the rows of our matrix. While we're on the first row, our program enters the nested loop, which doesn't impact the outer loop. The variable i represents the current row number;
  • for (int j = 0; j < twoDimensionalArray[0].length; j++) - The second for-loop iterates over the columns of the matrix. While we're on the 0th row, we iterate through the columns of that row. The variable j represents the current column number;
  • System.out.print(twoDimensionalArray[i][j] + " "); - In this line, we use System.out.print to display our values in a single line. Let's see how it operates: while we're on the 0th row, we iterate through the columns on that row. For example, array[0][1], followed by array[0][2], and so on. We continue through the columns as long as j is less than array[0].length. Once we reach array[0].length, we return to the outer array and move to the first row. For example, array[0][3] -> array[1][0]. We've reached our boundaries and then transitioned to row 1.
Task
test

Swipe to show code editor

Your task is to locate and display the diagonal (from the top-left corner to the bottom-right corner) of the provided matrix on the screen:

Note

The diagonal represents a line in the matrix where the row and column numbers are identical.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 4. Chapter 5
toggle bottom row

bookIteration In Two-Dimensional Array

How to Iterate Inside Two-Dimensional Array Using a for-loop?

Iterating through a two-dimensional array can be a bit challenging to grasp initially, so don't worry if it doesn't click right away. In this chapter, I'll demonstrate how to do it and explain how it functions.

We use a nested loop to iterate through a two-dimensional array, meaning one loop inside another. The outer loop iterates over the rows, while the inner loop iterates over the columns. Let's examine the syntax for iterating through a two-dimensional array using the example array we created in the previous chapter:

java

Main

copy

              
12345678910111213141516

            
package com.example;

public class Main {
    public static void main(String[] args) {
        int[][] twoDimensionalArray = { {1, 2, 3, 4},
                                        {5, 6, 7, 8},
                                        {9, 10, 11, 12},
                                        {13, 14, 15, 16} };
        for (int i = 0; i < twoDimensionalArray.length; i++) {
            for (int j = 0; j < twoDimensionalArray[0].length; j++) {
                System.out.print(twoDimensionalArray[i][j] + " ");
            }
          System.out.println();
        }
    }
}

Let's delve into the meaning of each element in the code snippet provided above:

  • int[][] twoDimensionalArray = - This line initializes a two-dimensional array;
  • for (int i = 0; i < twoDimensionalArray.length; i++) - The first for-loop iterates over the rows of our matrix. While we're on the first row, our program enters the nested loop, which doesn't impact the outer loop. The variable i represents the current row number;
  • for (int j = 0; j < twoDimensionalArray[0].length; j++) - The second for-loop iterates over the columns of the matrix. While we're on the 0th row, we iterate through the columns of that row. The variable j represents the current column number;
  • System.out.print(twoDimensionalArray[i][j] + " "); - In this line, we use System.out.print to display our values in a single line. Let's see how it operates: while we're on the 0th row, we iterate through the columns on that row. For example, array[0][1], followed by array[0][2], and so on. We continue through the columns as long as j is less than array[0].length. Once we reach array[0].length, we return to the outer array and move to the first row. For example, array[0][3] -> array[1][0]. We've reached our boundaries and then transitioned to row 1.
Task
test

Swipe to show code editor

Your task is to locate and display the diagonal (from the top-left corner to the bottom-right corner) of the provided matrix on the screen:

Note

The diagonal represents a line in the matrix where the row and column numbers are identical.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Everything was clear?

How can we improve it?

Thanks for your feedback!

How to Iterate Inside Two-Dimensional Array Using a for-loop?

Iterating through a two-dimensional array can be a bit challenging to grasp initially, so don't worry if it doesn't click right away. In this chapter, I'll demonstrate how to do it and explain how it functions.

We use a nested loop to iterate through a two-dimensional array, meaning one loop inside another. The outer loop iterates over the rows, while the inner loop iterates over the columns. Let's examine the syntax for iterating through a two-dimensional array using the example array we created in the previous chapter:

java

Main

copy

              
12345678910111213141516

            
package com.example;

public class Main {
    public static void main(String[] args) {
        int[][] twoDimensionalArray = { {1, 2, 3, 4},
                                        {5, 6, 7, 8},
                                        {9, 10, 11, 12},
                                        {13, 14, 15, 16} };
        for (int i = 0; i < twoDimensionalArray.length; i++) {
            for (int j = 0; j < twoDimensionalArray[0].length; j++) {
                System.out.print(twoDimensionalArray[i][j] + " ");
            }
          System.out.println();
        }
    }
}

Let's delve into the meaning of each element in the code snippet provided above:

  • int[][] twoDimensionalArray = - This line initializes a two-dimensional array;
  • for (int i = 0; i < twoDimensionalArray.length; i++) - The first for-loop iterates over the rows of our matrix. While we're on the first row, our program enters the nested loop, which doesn't impact the outer loop. The variable i represents the current row number;
  • for (int j = 0; j < twoDimensionalArray[0].length; j++) - The second for-loop iterates over the columns of the matrix. While we're on the 0th row, we iterate through the columns of that row. The variable j represents the current column number;
  • System.out.print(twoDimensionalArray[i][j] + " "); - In this line, we use System.out.print to display our values in a single line. Let's see how it operates: while we're on the 0th row, we iterate through the columns on that row. For example, array[0][1], followed by array[0][2], and so on. We continue through the columns as long as j is less than array[0].length. Once we reach array[0].length, we return to the outer array and move to the first row. For example, array[0][3] -> array[1][0]. We've reached our boundaries and then transitioned to row 1.
Task
test

Swipe to show code editor

Your task is to locate and display the diagonal (from the top-left corner to the bottom-right corner) of the provided matrix on the screen:

Note

The diagonal represents a line in the matrix where the row and column numbers are identical.

Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
Section 4. Chapter 5
Switch to desktopSwitch to desktop for real-world practiceContinue from where you are using one of the options below
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