What does the substring method of the String class do?
- Checks if the string is empty.
- Converts the string to lowercase.
- Retrieves the string's length.
- Returns a new string with a portion of the original string.
The substring() method of the String class in Java returns a new string that is a subset of the original string. It takes two parameters, the starting index and the ending index, and extracts the characters within that range, creating a new string. The other options do not describe the functionality of the substring() method.
Which of the following statements about the 'this' keyword is incorrect?
- 'this' can be used to call other class constructors from within a constructor.
- 'this' is used to reference the current instance of the class.
- 'this' is used to create a new object of the class.
- 'this' can be used to access instance variables and methods of the class.
The 'this' keyword in Java is primarily used to refer to the current instance of a class. It can be used to access instance variables and methods, and also to call other constructors of the same class. Option 3 is incorrect; 'this' does not create a new object but references the existing instance. Options 1, 2, and 4 are correct statements.
What is the purpose of serialization in Java?
- To convert objects into a byte stream
- To create new objects
- To perform mathematical calculations on objects
- To sort objects
Serialization in Java is primarily used to convert objects into a byte stream so that they can be easily stored, transmitted over a network, or reconstructed at a later time. This is especially useful for saving object state, such as in file I/O or network communication.
What does the Future interface represent in Java concurrency?
- A class for creating threads in Java
- A class for handling exceptions thrown by threads
- A class for storing past execution results
- A representation of a result that is yet to be computed
The Future interface in Java represents a result that is yet to be computed. It is used in concurrency to obtain the result of asynchronous operations. It allows you to check if the computation is complete, cancel the computation, and retrieve the result when it becomes available. This is commonly used with the Executor framework to manage concurrent tasks.
What is the primary purpose of the float property in CSS?
- To apply text styles such as font size and color.
- To create flexible grid layouts.
- To make text italic.
- To position an element to the left or right, allowing content to flow around it.
The primary purpose of the float property in CSS is to position an element to the left or right within its containing element. This allows other content to flow around it, which is commonly used for creating multi-column layouts or wrapping text around images.
The text-indent property in CSS is used to adjust ________.
- letter spacing
- line height
- text alignment
- the first line of a block of text
The "text-indent" property in CSS is used to adjust the indentation of the first line of a block of text. It specifies the amount by which the first line of a block-level element should be indented from the left margin.
In Flexbox, how would you align all items to the center of the container both vertically and horizontally?
- Apply justify-content: center and align-items: center.
- Apply margin: auto to all flex items.
- Set display: flex; and align-content: center.
- Use text-align: center on the container element.
To align all items both vertically and horizontally in a Flexbox container, you can use justify-content: center to center items horizontally and align-items: center to center them vertically. This combination ensures that items are centered in the container along both axes.
Which CSS property is used to control the time between the end of one animation iteration and the start of the next?
- animation-delay
- animation-duration
- animation-play-state
- animation-timing-function
The animation-delay property is used to control the time between the end of one animation iteration and the start of the next. It specifies a delay before the animation begins and can be helpful for creating timed animations and controlling their sequence.
You want to set a global color scheme for a website using CSS variables. Where would be the best place to define these custom properties?
- In a separate CSS variables file
- In an external CSS file
- In the CSS for each individual element
- In the HTML section
To set a global color scheme for a website using CSS variables, it's best to define these custom properties in an external CSS file. This allows you to centralize your variable definitions, making it easier to maintain and update the color scheme across your entire website. While you can define CSS variables in other places like the HTML section or inline CSS for specific elements, it's not as efficient or maintainable for global color schemes.
In SCSS, the @import directive allows you to ________.
- Create a new CSS class
- Define variables
- Import external CSS files
- Set media queries
The @import directive in SCSS is used to import external CSS files into your SCSS code. It's a way to modularize your styles and manage them in separate files, promoting better organization and maintainability.
You're designing a photo gallery using a grid layout. Each row should display three images. The middle image in each row should be twice as large as the images on its sides. How would you achieve this?
- Use grid-template-areas property.
- Apply grid-row: span 2 to the middle image.
- Use grid-template-columns with explicit column sizes.
- Set grid-auto-flow: dense.
To achieve this layout, you should apply grid-row: span 2 to the middle image. This CSS rule will make the middle image span two rows, making it twice as large as the other images in the row.
What is the role of the src attribute inside the @font-face rule?
- Defines the font color
- Sets the font style
- Specifies the font size
- Specifies the font's source file location
Inside the @font-face rule, the "src" attribute is used to specify the font file's source location. This attribute tells the browser where to find and load the font file, allowing you to use custom fonts in your web design. It typically points to the location of a font file using a URL or local file path.