Java System.out.println()
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System.out.println(value);
System.out.print(value);Basic Printing
println() converts whatever you pass it (numbers, strings, objects) into its text form and writes it to the console, then moves the output cursor to the start of the next line automatically.
Example: Basic Printing
// Define the class Main
public class Main {
// Program entry point: the JVM starts running here
public static void main(String[] args) {
// Print a line to the console
System.out.println(42);
// Print a line to the console
System.out.println("moves to the next line automatically");
}
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print() vs println()
print() leaves the cursor right where the output ended, so a second print() call continues on the same line -- useful for building up one line of output across multiple statements, unlike println().
Example: print() vs println()
public class Main {
public static void main(String[] args) {
System.out.print("Same ");
System.out.print("line"); // continues right where the last print ended
}
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Concatenating Output
Using the + operator inside println(), like println("Score: " + score), converts non-string values to text and joins them into a single string before printing -- Java evaluates left to right.
Example: Concatenating Output
public class Main {
public static void main(String[] args) {
int score = 90;
System.out.println("Score: " + score); // non-string joined into one string
}
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Printing Expressions
Java computes any arithmetic inside the parentheses first -- println(2 + 3) prints 5, not the literal text "2 + 3" -- so mixing math and string concatenation in one line requires care with operator precedence.
Example: Printing Expressions
public class Main {
public static void main(String[] args) {
System.out.println(2 + 3); // prints 5, not the text "2 + 3"
}
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Special Escape Characters
Escape sequences like \n (newline) and \t (tab) let you control spacing and line breaks inside a single string literal without needing multiple print statements.
Example: Special Escape Characters
// Define the class Main
public class Main {
// Program entry point: the JVM starts running here
public static void main(String[] args) {
// Print a line to the console
System.out.println("Line one\nLine two\tTabbed");
}
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- Using
print()when you want a new line, so the next output appears on the same line. - Forgetting to escape quotes inside a string, as in
"He said "hi"", which is a compile error; use\". - Writing
System.out.println("a" + 1 + 2)and expecting arithmetic, when the numbers are joined as text.
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