Java Keywords List and Basic Java Syntax

Java keywords are reserved words with a special meaning, like class, if, and return. You can't use them as names for your own variables or classes. This page lists all Java keywords with a plain-English meaning for each, plus the basic syntax rules every Java program follows.

What are keywords in Java?

A keyword is a word the Java compiler already understands. When it sees while, it knows a loop is starting. Because these words are taken, int while = 3; won't compile. Every Java keyword is written in lowercase.

Types of keywords in Java

It's much easier to remember keywords in groups. Pick a group to see its members:

Complete list of all Java keywords

All 51 reserved keywords, in alphabetical order. Links go to our in-depth guides:

Contextual keywords in modern Java

New Java versions needed new keywords without breaking old code that might use those words as variable names. The solution: contextual keywords, which only have special meaning in a specific position.

var names = new java.util.ArrayList<String>();      // var: type inferred as ArrayList<String>

record Point(int x, int y) { }                       // record: fields, constructor, equals, toString for free

String size = switch (names.size()) {                // switch expression
    case 0 -> "empty";
    case 1, 2, 3 -> "small";
    default -> {
        yield "large";                               // yield: value from a block
    }
};

Basic Java syntax rules

Beyond keywords, every Java file follows a handful of rules. Here's a small program that shows them all:

package com.example.shop;            // 1. optional package line comes first

import java.util.List;                // 2. imports next

/** 3. Javadoc comment describing the class */
public class PriceList {              // 4. public class name == file name (PriceList.java)

    private static final int MAX_ITEMS = 100;   // 5. constants in UPPER_SNAKE_CASE

    public static void main(String[] args) {
        List<Double> prices = List.of(4.5, 10.0, 2.25);
        double total = 0;                       // 6. statements end with ;

        for (double price : prices) {           // 7. blocks use { }
            total += price;                     // single-line comment
        }
        System.out.println("Total: " + total);
    }
}

Total: 16.75

Quick recap

What's next?

Dive into the keywords beginners find trickiest: this, super, static, and final.