Java 배열

배열의 생성과 초기화

• 자바에서 배열은 객체다. 
• 배열을 선언하는 것을 보자 

// A basic type of declaration.
// false for boolean array, 0 for int array,
// and null for Object array are default values.
// They are set automatically when the arrays are initialized.
int [] intArray = new int[4]; 
 
// Particular numbers are assigned when an array is declared.
int [] intArray = {1, 2, 3, 4}; 
 
// Of course, declaration and assignment can be separated.
int [] intArray; // null is assined to this array at this moment 
                 // because array is also an object. 
intArray = new int[] {1, 2, 3, 4}; 
 
// Declaration, object creation, and assignment are all separated.
boolean [] boolArray; // null is assined to this array at this moment
                      // because array is also an object.
boolArray = new boolean[4]; // the address of the object is assigned to the variable 
Arrays.fill(boolArray, true); // Arrays.fill() is used 
                              // when the one value is assigned to all elements.

• 배열은 객체이므로 변수에는 null이 들어가거나 객체의 주소가 들어간다. 
• 생성만 하면 초기값이 자동으로 할당되는 것에 주의하자.

2차원 배열

• for-each를 이용하여 iteration 하기

String properties[][] = {
                {"application_id", "text"}, {"sample_time", "integer"},
                };
 
for (String[] propertyInfo : properties) {
    System.out.println(propertyInfo[0] + ": " + propertyInfo[1]);
}
// or
for (String[] propertyInfo : properties) {
    for (String detail : propertyInfo) {
        System.out.println(detail);
    }
}