The maximum size of a single Java method’s bytecode is 65,535 bytes.
The limit comes from the Java class-file format’s Code attribute. Its code_length field must be greater than zero and less than 65,536, so the largest legal code array contains 65,535 bytes. This is a limit on the compiled Java Virtual Machine instruction array, not on the number of source-code characters, statements, or lines in a method.
The distinction matters because Java source can compile into bytecode of very different sizes. A compact-looking method may generate many instructions, especially when it contains large switch statements, repeated expressions, or complex control flow. Conversely, constants and compiler optimizations can affect the resulting representation. A method that exceeds the limit commonly causes a compiler error such as “code too large.”
The limit also does not include every part of a method’s class-file representation. Exception-handler entries, line-number metadata, local-variable metadata, and other attributes accompany the code array. Developers usually solve an oversized-method error by splitting the method into smaller helpers, simplifying generated code, or changing code-generation strategies. The nearby value 65,536 is the exclusive upper boundary, not the permitted maximum.