编码练习——Java-3-数组
2017-05-01 21:31
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创建与输出数组
数组 - 实例 - 求一位数组各元素的和public class Test { public static void main(String[] args) { int[] num = {1,2,3,4,5,6,7,8,9,10}; int sum = 0; System.out.println("一维数组中各元素的和是:"); for (int i=0; i<num.length; i++) { if(i==9) System.out.print(num[i] + "="); else System.out.print(num[i] + "+"); sum = sum + num[i]; } System.out.println(sum); } }123456789101112131415123456789101112131415数组 - 实例 - 获取一维数组的最小值
public class Test { public static void main(String[] args) { int[] num = {8,3,4,1,6,10}; System.out.println("输出一维数组:"); for (int i=0; i<num.length; i++) { System.out.print(num[i] + " "); } int min = num[0]; for(int j=0; j<num.length-1; j++) { if (min > num[j+1]) { min = num[j+1]; } } System.out.println("\n一维数组的最小值是:" + min); } }123456789101112131415161718123456789101112131415161718二维数组 - 输出 Java创建数组后,将元素初始化为0.
public class Test { public static void main(String[] args) { int a[][] = new int[3][4]; System.out.println("输出3行4列的数组:"); for (int i=0; i<a.length; i++){ for (int j=0; j<a[i].length; j++) { System.out.print(a[i][j] + " "); } System.out.println(); } } }1234567891011121312345678910111213三维数组 - 输出
public class Test { public static void main(String[] args) { int arr[][][] = new int[][][] { {{1,2,3},{4,5,6}}, {{7,8,9},{10,11,12}}, {{13,14,15},{16,17,18}} }; for (int i=0; i<arr.length; i++) { System.out.println("三维数组的第" + (i+1) + "个元素是一个"+arr[i].length + "维数组,内容如下:"); for(int j=0; j<arr[i].length; j++) { for (int k=0; k<arr[i][j].length; k++) { System.out.print(arr[i][j][k] + "\t"); } System.out.println(); } } } }1234567891011121314151617181912345678910111213141516171819实例 - 对矩阵进行转置运算
public class Test { public static void main(String[] args) { int arr[][] = new int[][] {{1,2,3},{4,5,6},{7,8,9}}; System.out.println("转置前的矩阵是:"); printArray(arr); int arr2[][] = new int[arr.length][arr.length]; for(int i=0; i<arr.length; i++) { for(int j=0; j<arr[i].length; j++) arr2[j][i] = arr[i][j]; } System.out.println("转置后的矩阵是:"); printArray(arr2); } private static void printArray(int[][] arr) { for (int i=0; i<arr.length; i++) { for (int j=0; j<arr.length; j++) { System.out.print(arr[i][j] + " "); } System.out.println(); } } }1234567891011121314151617181920212223242512345678910111213141516171819202122232425实例 - 求方阵的迹
public class Test { public static void main(String[] args) { int arr[][] = new int[][] {{1,2,3}, {4,5,6}, {7,8,9}}; int tr = 0; System.out.println("方阵arr[][]是:"); for (int i=0; i<arr.length; i++) { for (int j=0; j<arr.length; j++) { System.out.print(arr[i][j] + " "); } System.out.println(); } for (int i=0; i<arr.length; i++) tr += arr[i][i]; System.out.println("方阵arr[][]的迹是:" + tr); } }12345678910111213141516171234567891011121314151617
数组的基本操作
数组的基本操作 - 遍历一维数组public class Test { public static void main(String[] args) { int day[] = new int[] {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; for (int i=0; i<12; i++) { System.out.print((i+1) + "月有" + day[i] + "天" + "\t\t"); if ((i+1)%3==0) System.out.println("\n"); } } }1234567891012345678910数组的基本操作 - 遍历二维数组
public class Test { public static void main(String[] args) { int b[][] = new int[][] {{1}, {2,3}, {4,5,6}}; System.out.println("二维数组是:"); for (int k=0; k<b.length; k++) { for (int c = 0; c<b[k].length; c++) { System.out.print(b[k][c] + " "); } System.out.println(); } } }123456789101112123456789101112数组的基本操作 - 遍历二维数组(foreach)
public class Test { public static void main(String[] args) { int arr2[][] = new int[][] {{3,4,3}, {1,2}}; for (int x[]:arr2) { for (int e : x) { System.out.print(e + " "); } System.out.println(); } } }12345678910111234567891011数组的基本操作 - 填充数组元素(fill)
import java.util.Arrays; public class Test { public static void main(String[] args) { int arr[] = new int[5]; Arrays.fill(arr, 8); for (int i=0; i<arr.length; i++) System.out.println("第" + (i+1) + "个元素是:" + arr[i]); } }123456789123456789数组的基本操作 - 填充数组元素(fill)
import java.util.Arrays; public class Test { public static void main(String[] args) { int arr[] = new int[] {45, 12, 2, 10, 1}; Arrays.fill(arr, 1, 3, 8); for (int i=0; i<arr.length; i++) { System.out.println("第" + (i+1) + "个元素是:" + arr[i]); } } }12345678910111234567891011数组的基本操作 - 排序
import java.util.Arrays; public class Test { public static void main(String[] args) { int arr[] = new int[] {23, 42, 12, 8, 5, 10}; System.out.println("原一维数组是:"); for (int i=0; i<arr.length; i++) { System.out.print(arr[i] + " "); } Arrays.sort(arr); System.out.println("\n升序排列后的数组是:"); for (int i=0; i<arr.length; i++) { System.out.print(arr[i] + " "); } } }123456789101112131415123456789101112131415数组的基本操作 - 复制
import java.util.Arrays; public class Test { public static void main(String[] args) { int arr[] = new int[] {23, 42, 12}; System.out.println("复制前的数组是:"); for (int i=0; i<arr.length; i++) { System.out.print(arr[i] + " "); } int newarr[] = Arrays.copyOf(arr, 5); System.out.println("\n复制后的数组是:"); for (int i=0; i<newarr.length; i++){ System.out.print(newarr[i] + " "); } } }1234567891011121314151612345678910111213141516数组的基本操作 - 复制
import java.util.Arrays; public class Test { public static void main(String[] args) { int arr[] = new int[] {23, 42, 12, 84, 10}; System.out.println("复制前的数组是:"); for (int i=0; i<arr.length; i++) { System.out.print(arr[i] + " "); } int newarr[] = Arrays.copyOfRange(arr, 0, 3); System.out.println("\n将数组下标0~3复制到新数组中:"); for (int i=0; i<newarr.length; i++){ System.out.print(newarr[i] + " "); } } }123456789101112131415123456789101112131415实例 - 对比一维、二维数组所占内存
public class Test { public static void main(String[] args) { int num1 = 1024*1024*2; int[] arr1 = new int[num1]; for (int i=0; i<arr1.length; i++) arr1[i] = i; //获得占用内存总数,并将单位转换为MB long memory1 = Runtime.getRuntime().totalMemory()/1024/1024; System.out.println("用一维数组存储占用内存总量为:" + memory1); int num2 = 1024*1024; int[][] arr2 = new int[num2][2]; for(int i=0; i<arr2.length; i++) { arr2[i][0] = i; arr2[i][1] = i; } long memory2 = Runtime.getRuntime().totalMemory()/1024/1024; System.out.println("用二维数组存储占用的内存总量为:" + memory2); } }1234567891011121314151617181912345678910111213141516171819实例 - 使用直接插入排序法排序
public class Test { public static void main(String[] args) { int[] array = new int[] {20, 40, 90, 30, 80, 70, 50}; System.out.println("排序前:"); for (int i=0; i<array.length; i++) { System.out.print(array[i] + " "); } int tmp; int j; for (int i=1; i<array.length; i++) { tmp = array[i]; for (j=i-1; j>=0 && array[j] > tmp; j--) { array[j+1] = array[j]; } array[j+1] = tmp; } System.out.println("\n排序后:"); for (int i=0; i<array.length; i++) { System.out.print(array[i] + " "); } } }1234567891011121314151617181920212212345678910111213141516171819202122实例 - 冒泡排序
public class Test { public static void main(String[] args) { int[] array = new int[] {63, 4, 24, 1, 3, 13}; System.out.println("冒泡排序法的过程是:"); for (int i=1; i<array.length; i++) { for (int j=0; j<array.length-i; j++) { if (array[j] > array[j+1]) { int tmp = array[j]; array[j] = array[j+1]; array[j+1] = tmp; } System.out.print(array[j] + " "); } System.out.print("【"); for (int j=array.length-i; j<array.length; j++) { System.out.print(array[j] + " "); } System.out.println("】"); } } }
from: http://blog.csdn.net/xuezhisdc/article/details/52185250[/code]
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