Control Flow in Java

Control flow determines the order in which statements are executed in a Java program. Java provides several control flow structures: conditional, looping, and branching statements.

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1. Conditional Statements

if, else if, else

Used to execute code blocks based on boolean conditions.

var x = 10;
if (x > 0) {
    System.out.println("Positive");
} else if (x < 0) {
    System.out.println("Negative");
} else {
    System.out.println("Zero");
}

switch

Used to simplify multiple if-else branches based on constant values.

var day = 3;
switch (day) {
    case 1 -> System.out.println("Sunday");
    case 2 -> System.out.println("Monday");
    default -> System.out.println("Other day");
}

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2. Looping Statements

for loop

for (int i = 0; i < 5; i++) {
    System.out.println(i);
}

while repeats as long as a condition is true.

int i = 0;
while (i < 5) {
    System.out.println(i);
    i++;
}

do-while executes at least once before checking the condition.

int i = 0;
do {
    System.out.println(i);
    i++;
} while (i < -1);

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3. Branching Statements

break can end a loop.

for (int i = 0; i < 10; i++) {
    if (i == 5) break;
    System.out.println(i);
}

continue skips the current iteration and moves to the next.

for (int i = 0; i < 5; i++) {
    if (i == 2) continue;
    System.out.println(i);
}

return exits from the current method.

public void greet(String name) {
    if (name == null) return;
    System.out.println("Hello, " + name);
}

Nested loops are loops inside loops. You can use break or continue in the inner or outer loop. If break or continue in the inner loop, it will continue or breake the inner loop

for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 3; j++) {
        if (j == 2) continue;
        System.out.println("i=" + i + ", j=" + j);
    }
}

If you want to continue or break a specific loop, you can use a label

outer : for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 3; j++) {
        if (j == 2) break outer;
        System.out.println("i=" + i + ", j=" + j);
    }
}