If the following lines were in a method and the method was executed, line 2would print " counts = null" because the array object has notyet been constructed. M圜lass things // a two-dimensional array of objects boolean flags // extra spaces are not significant4. Here are someexamples of declaring variables that are arrays of primitives (lines 1 through3) and objects (lines 4 and 5): 1. Like other variables, arrays must be declared before you use them.Declaration can be separate from the actual creation of the array. Theimportant point to remember is that when created, primitive arrays will havedefault values assigned, but object references will all be null. You can have arrays of any of the Java primitives or reference variables. Java arrays are one dimensional, but an arraycan contain other arrays, which gives the effect of multiple dimensions. Every array has an associated lengthvariable, established when the array is created, which you can access directly.If you try to address an element with an index that is outside the range of thearray, an exception is generated. The first element in an array has an index of 0.Īll of these contained variables, or elements, must be the same type, whichis the type of the array. Java 2 Programmer Exam Cram 2 (Exam Cram CX-310-035)Īn array in Java is a type of object that can contain a number of variables.These variables can be referenced only by the array indexa nonnegativeinteger.
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