Decisions

The idea

An if statement chooses a branch according to a boolean condition. An else belongs to the nearest unmatched if, so braces help communicate the intended structure. In an if/else-if chain, only the first true branch runs. Arrange overlapping conditions deliberately: checking a broad condition first can make a more specific case unreachable. Boundary examples often reveal mistakes that ordinary inputs do not.

The operators && and || short-circuit. Java may skip their right operand once the outcome is known. This supports guards such as checking a reference for null before calling a method. Design the condition from the requirement, then test values just below, at, and above every threshold.

public class Main {
  public static void main(String[] args) {
    int points = 80;
    if (points >= 90) {
      System.out.println("gold");
    } else if (points >= 70) {
      System.out.println("silver");
    } else {
      System.out.println("practice");
    }
  }
}

silver

The first comparison is false. The second is true, so the remaining alternative is skipped.