(1)今天做了什么; (2)明天准备做什么? (3)遇到的问题,如何解决?
今天学习了菜鸟教程Java实例,数组
1.数组的排序和元素的查找——sort和binarySearch方法
import java.util.Arrays; public class Main { public static void main(String[] args) { int array[] = { 2, 5, -2, 6, -3, 8, 0, -7, -9, 4 }; Arrays.sort(array); printArray("数组排序结果为",array); int index = Arrays.binarySearch(array,2); System.out.println("元素 2 在第 "+ index +" 个位置"); } public static void printArray(String message,int[] array) { System.out.println(message + ": [length: " + array.length + "]"); for(int i = 0; i < array.length; i++) { if(i != 0) { System.out.print(","); } System.out.print(array[i]); } System.out.println(); } }
2.数组添加元素
import java.util.Arrays; public class Main { public static void main(String[] args) { int array[] = { 2, 5, -2, 6, -3, 8, 0, -7, -9, 4 }; Arrays.sort(array); printArray("数组排序",array); int index = Arrays.binarySearch(array, 1); System.out.println("元素 1 所在位置(负数为不存在):" + index); int newIndex = -index - 1; array = insertElement(array,1,newIndex); printArray("数组添加元素 1 后",array); } private static void printArray(String message,int[] array) { System.out.println(message + "[length: " +array.length+"]"); for(int i = 0; i < array.length; i++) { if(i != 0) System.out.print(","); System.out.print(array[i]); } System.out.println(); } private static int[] insertElement(int []original,int element,int index) { int length = original.length; int[] destination = new int[length + 1]; System.arraycopy(original, 0, destination, 0, index); destination[index] = element; System.arraycopy(original, index, destination, index+1, length - index); return destination; } }
3.获取数组长度——length方法
public class Main { public static void main(String args[]) { String[][] data = new String[2][5]; System.out.println("第一维数组长度: " + data.length); System.out.println("第二维数组长度: " + data[0].length); } }
4.数组反转
5.数组输出
public class Welcome { public static void main(String[] args){ String[] runoobs = new String[3]; runoobs[0] = "菜鸟教程"; runoobs[1] = "菜鸟工具"; runoobs[2] = "菜鸟笔记"; for (int i = 0; i < runoobs.length; i++){ System.out.println(runoobs[i]); } } }
6.数组获取最大和最小值