Summary - String basics

Combine length, substring and format to write a business card.

Summary - String basics

In this group you learned String methods:

length/charAt: length and character access
equals/equalsIgnoreCase: content comparison
indexOf/substring: search and slice
toUpperCase/trim: transformation
String.format: formatting

These methods are the basic tools to process, search, transform and format string data. Now combine them and write a business card.

Exercise Write a business card

Write a Main class with a main method. Assign "Alex" to String name and "Engineer" to String title. Assign name + " - " + title to String card. Print card and card.length() with println.

Show example solution

public class Main {
    public static void main(String[] args) {
        String name = "Alex";
        String title = "Engineer";
        String card = name + " - " + title;
        System.out.println(card);
        System.out.println(card.length());
    }
}

Tips

A few tips from this group:

Always use equals for String comparison; == is not reliable.
Trim user input that may have extra spaces first.
Check indexOf result against -1.
Strings are immutable; assign transformations to a new variable.
Use String.format to format output.

Combined with conditionals and loops, these basics let you write powerful programs.

Exercise Business card with String.format

Write a Main class with a main method. Assign "Alex" to String name and 28 to int age. Assign String.format("%s - %d", name, age) to String card. Print card with println.

Show example solution

public class Main {
    public static void main(String[] args) {
        String name = "Alex";
        int age = 28;
        String card = String.format("%s - %d", name, age);
        System.out.println(card);
    }
}

Test yourself

Match the methods

length()

Length
equals()

Compare
substring()

Slice
format()

Format

Complete the substring call

String first = name.____(0, 1);

Show answer

String first = name.substring(0, 1);

Next lesson: The if statement

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