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Arrays의메소드

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Arrays

  • 배열의 출력 - toString()
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static String toString(boolean[] a)
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static String toString(byte[] a)
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static String toString(char[] a)
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static String toString(short[] a)
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static String toString(int[] a)
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static String toString(long[] a)
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static String toString(float[] a)
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static String toString(double[] a)
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static String toString(Object[] a)
  • 배열의 복사 - copyOf(), copyOfRange()
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int[] arr = {0,1,2,3,4};
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int[] arr2 = Arrays.copyOf(arr, arr.length);
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int[] arr3 = Arrays.copyOf(arr, 3);
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int[] arr4 = Arrays.copyOf(arr, 7);
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int[] arr5 = Arrays.copyOfRange(arr, 2, 4);
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int[] arr6 = Arrays.copyOfRange(arr, 0 ,7);
  • 배열 채우기 - fill(), setAll()
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int[] arr = new int[5];
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Array.fill(arr, 9); // arr=[9,9,9,9,9]
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Arrarys.setAll(arr, (i) -> (int)(Math.random()*5)+1); //arr=[1,5,2,1,1]
  • 배열의 정렬과 검색 - sort(), binarySearch()
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int[] arr = {3, 2, 0, 1, 4};
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int idx = Arrays.binarySearch(arr, 2);
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Arrays.sort(aa); //배열arr을정렬
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System.out.println(Arrays.toString(arr));
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int idx = Arrays.binarySearch(arr, 2); //idx=2
  • 다차원 배열의 출력 - deepToString()
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int[] arr = {0,1,2,3,4};
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int[][ arr2D = {{11,12}, {21,22}};
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System.out.println(Arrays.toString(arr)); //[0, 1, 2, 3, 4]
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System.out.println(Arrarys.deepToString(arr2D)); //[[11, 12], [21, 22]]
  • 다차원 배열의 비교 - deepEquals()
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String[][] str2D = new String[][]{{"aaa", "bbb"}, {"AAA", "BBB"}}
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String[][] str2D2 = new String[][]{{"aaa", "bbb"},{"AAA", "BBB"}};
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System.out.println(Arrays.equals(str2D, str2D2)); //false
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System.out.println(Arrays.deepEquals(str2D, str2D2)); //true
  • 배열을 List로 변환 - asList(Object....a)
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List list = Arrarys.asList(new Integer[]{1,2,3,4,5});
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List list = Arrays.asList(1,2,3,4,5);
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list.add(6);
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List list = new ArrayList(Arrays.asList(1,2,3,4,5));