Java Primitive Data Types: int, double, boolean—Are You Using Them Correctly?

Java is a strongly typed language where variables must have their data types explicitly defined. This article introduces the three most commonly used basic types: int, double, and boolean. - **int** is an integer type with a size of 4 bytes. Its range is from -2147483648 to 2147483647 (approximately -2.1 billion to 2.1 billion). It is used for counting, indexing, age, and other scenarios. Overflow issues should be noted: directly assigning values beyond the range (e.g., 2147483648) will cause compilation errors, and operations may also lead to implicit overflow (e.g., max + 1 = -2147483648). To resolve this, the long type should be used instead. - **double** is a decimal type with an 8-byte size and an extremely large range, suitable for scenarios like amounts and height. However, due to precision issues in binary storage (e.g., 0.1 cannot be precisely represented), comparisons should use BigDecimal or a difference judgment method. Exceeding the range will result in overflow to infinity. - **boolean** can only take values true or false, and is used for conditional and loop control. It can only be assigned true or false and cannot be used with 1/0 or arithmetic operations. In summary, selecting the appropriate type avoids corresponding pitfalls, and type matching is fundamental for a program to run correctly.