How to use if and else in java

The if and else statements in Java are conditional execution statements, used to execute different code blocks based on conditional judgments. Syntax: if (condition) {execute code block} else {execute code block}. condition is a Boolean expression that evaluates to true or false. Nested if statements can create more complex condition checks. Example: Check if num is greater than 0, if so, print "positive number", otherwise print "non-positive number".

Usage of if and else statements in Java

What are if and else statements?

if and else statements are conditional execution statements, used to execute different code blocks based on conditional judgments.

Syntax:

<code class="java">if (condition) {
    // 如果 condition 为 true，执行此代码块
} else {
    // 如果 condition 为 false，执行此代码块
}</code>

where condition is a Boolean expression that evaluates to true or false.

How to use if and else statements?

1. Check condition: Use Boolean expression to check condition.
2. Execute code block: If the condition is true, the first code block is executed; if the condition is false, the second code block is executed.
3. Nested if statements: If statements can be nested together to create more complex condition checks.

Example:

<code class="java">int num = 10;

if (num > 0) {
    System.out.println("正数");
} else {
    System.out.println("非正数");
}</code>

In this example, if num is greater than 0, print "positive number"; otherwise, print " Non-positive number".

Supplementary Note:

• The else clause is optional and should only be used when different code needs to be executed when the condition is false. Boolean expressions in
• condition can be simple comparisons (e.g. num > 0) or more complex expressions (e.g. num % 2 == 0).
• Additional condition checks can be added using the else if statement.

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