What is the usage method of the ‘if’ function in Java?

In Java, the if statement is used to control the flow of a program and execute different code blocks based on certain conditions. The basic syntax of the if statement is as follows:

if (condition) {
    // 如果条件为真，执行这里的代码块
} else {
    // 如果条件为假，执行这里的代码块（可选）
}

In an if statement, the condition is a boolean expression. If the expression results in true, the code in the if block is executed. If it results in false, the code in the else block (optional) is executed. It is up to individual circumstances whether to use the else block or not.

In addition to using standalone if statements, you can also use an if-else if-else chain to evaluate multiple conditions, with the following syntax:

if (condition1) {
    // 如果条件1为真，执行这里的代码块
} else if (condition2) {
    // 如果条件2为真，执行这里的代码块
} else {
    // 如果条件1和条件2都为假，执行这里的代码块
}

This allows different code blocks to be executed based on different conditions. In actual development, the if statement is often combined with other control flow statements to achieve more complex logical control.