Java數組的使用方法

1. 數組

創建一個數組

public class Mode3 {
	public static void main(String[] args) {
		int[] arr1 = new int[3];
		System.out.println(arr1);
		arr1 = new int[4];
		System.out.println(arr1);
	}
}

2. 遍歷數組

package mode4;

public class Mode4 {
	public static void main(String[] args) {
		int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8 };
		for (int a = 0; a < arr.length; a++) {
			System.out.println(arr[a]);
		}
	}
}

3. 取出數組中的最大值

package mode4;

public class Mode4 {
	public static void main(String[] args) {
		System.out.println(getMax());
	}

	public static int getMax() {
		int a = 0;
		int[] arr = { 12, 3, 4, 5, 6, 7, 5, 446, 46, 4684, 68 };
		for (int i = 0; i < arr.length; i++) {
			// 找一個變量來暫時存儲數組中較大的值，直到遍歷完打印即可
			if (arr[i] > a) {
				a = arr[i];
			} else {
				a = a;
			}
		}
		return a;
	}
}

4. 數組元素反轉

1.使用兩個數組，直接顛倒

package mode4;

public class Mode5 {
	public static void main(String[] args) {
		// 數組的反轉

		int[] arr = { 1, 2, 3, 4, 5, 6 };
		int[] arr0 = new int[arr.length];
		for (int i = 0; i < arr.length; i++) {
			arr0[i] = arr[arr.length-(i+1)];
		}
		for (int i = 0; i < arr0.length; i++) {
			System.out.println(arr0[i]);
		}
	}
}

2. 使用第三個空變量進行值的傳遞

package mode4;

public class Mode5 {
	public static void main(String[] args) {
		getChange();
	}

	public static void getChange() {
		int[] arr1 = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
		int temp;
		for (int i = 0; i < (arr1.length) / 2; i++) {
            //外部循環不能到全部的數組，因爲全部遍歷就都換了，所以要留下一半不要換
			temp = arr1[i];
			arr1[i] = arr1[arr1.length - 1 - i];
			arr1[arr1.length - 1 - i] = temp;
		}
		for (int i = 0; i < arr1.length; i++) {
			System.out.println(arr1[i]);
		}
	}
}

5. 定義方法以數字作爲返回值

package mode4;

public class Mode6 {
	public static void main(String[] args) {
		System.out.println(getArr()[1]);
	}

	public static int[] getArr() {
		int a = 10;
		int b = 20;
		int[] arr = new int[] { a, b };
		return arr;
	}
}

任何數據類型都可以作爲返回值。