The String type: strings and text

1. The String type

The String type is one of the most used types in Java. It just might be the most used type. There's a reason why it is so popular: such variables let you store text — and who doesn't want to do that? Additionally, unlike the int and double types, you can call methods on objects of the String type, and these methods do some useful and interesting things.

What's more, all Java objects (all of them!) can be transformed into a String. Well, to be more precise, all Java objects can return a text (string) representation of themselves. The name of the String type starts with a capital letter, because it is a full-fledged class.

We'll return to this type more than once (it is super useful and interesting), but today we will make a brief introduction.

2. Creating String variables

The String type is designed for storing strings (text). To create a variable in code that can store text, you need to use a statement like this:

String name;

Where name is the name of the variable.

Examples:

String name;

String message;

String text;

Just as with the int and double types, you can use the shorthand notation to create multiple String variables:

String name1, name2, name3;

3. Assigning values to String variables

To put a value into a String variable, you need to this statement:

name = "value";

And now we have come upon the first difference between this type and those we have already studied. All values of the String type are strings of text and must be enclosed in double quotes.

Examples:

String name = "Steve";

String city = "New York";

String message = "Hello!";

4. Initializing String variables

As with the int and double types, variables of the String type can be initialized immediately when they are created. In fact, this is something you can do with all types in Java. So we won't mention it anymore.

String name1 = "value1", name2 = "value2", name3 = "value3";

String name = "Steve", city = "New York", message = "Hello!";

This code won't work:

String name;
System.out.println(name);

int a;
a++;

double x;
double y = x;

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Task

New Java Syntax, level 2, lesson 3

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We solemnly publish and declare these variables...

Declare int variables called a and b. In the same line in which the variables are declared, immediately assign them different values. The values can be any integers.

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Task

New Java Syntax, level 2, lesson 3

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A variable on our screen

Declare a String variable called name. In the line where we declare the variable, immediately assign it some value. Display the variable "name" on the screen.

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Task

New Java Syntax, level 2, lesson 3

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One variable is not enough

Declare int variables a and b and String variable s. In the same line in which the variables are declared, immediately assign them any different values.

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Task

New Java Syntax, level 2, lesson 3

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Display the square of a number

The variable number is given. Write a program that displays the square of this variable: (number * number).

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