What does : in java mean?

The colon in Java is used in a variety of situations, including the ternary operator, switch statement labels, array declaration and initialization, variable declaration and initialization, field definitions in enumerations, and lambda expressions.

: in Java:

The colon (:) in Java is used in many situations, the main meanings are as follows ：

1. The ternary operator in conditional judgment

The usage format of the ternary operator isConditional expression? Value when the condition is met: The value when the condition is not met. It allows conditionals and assignments to be performed in a single line of code.

Example:

<code class="java">int age = 18;
String result = age >= 18 ? "成年人" : "未成年人";</code>

2. Case labels in the switch statement

In the switch statement, each case label They all start with a constant or expression followed by a colon, indicating the value to be checked.

Example:

<code class="java">switch (dayOfWeek) {
    case 1:
        System.out.println("星期一");
        break;
    case 2:
        System.out.println("星期二");
        break;
    ...
}</code>

3. Array declaration and initialization

When declaring an array, you can use a colon to specify the array type. Element type.

Example:

<code class="java">int[] numbers = new int[] {1, 2, 3, 4};</code>

4. Variable declaration and initialization

In Java 9 and above, you can use The colon initializes the variable when it is declared.

Example:

<code class="java">int number = 5;
String name = "John";</code>

5. Field definitions in enumerations

In enumerations, each enumeration A constant is followed by a colon and its value.

Example:

<code class="java">enum Season {
    SPRING: "春天",
    SUMMER: "夏天",
    FALL: "秋天",
    WINTER: "冬天"
}</code>

6. Lambda expression

In a lambda expression, the colon separates the parameter list from the lambda separated from the body of the expression.

Example:

<code class="java">Comparator<Integer> comparator = (a, b) -> a - b;</code>

The above is the detailed content of What does : in java mean?. For more information, please follow other related articles on the PHP Chinese website!