# arthas-watch > Method invoke data observation. > See also: `arthas`, `arthas-trace`. > More information: . - Observe the first parameter and return value of method, and expand the nested attributes of the object to 4 levels: `watch {{class-pattern}} {{method-pattern}} {{'{ params[0],returnObj }'}} -x 4` - When the value of the first parameter of the method is 5, the second parameter and return value are output, and the object is expanded 4 layers: `watch {{class-pattern}} {{method-pattern}} {{'{ params[1],returnObj }'}} {{'"5".equals(params[0])'}} -x 4` - When the method returns or an exception occurs, observe the count property of the second parameter: `watch {{class-pattern}} {{method-pattern}} {{'{ params[1].count }'}} -e -s`