Java数组，字符串

数组定义

数据类型 名称[] = new 数据类型[n]

int data[] = new int[3];
		data[0] = 10;
		data[1] = 11;
		data[2] = 25;

一步定义数组，并循环输出

int data[] = new int[] {1,2,3,4};
		for (int i : data) {
	        System.out.println(i);
	    }

字符串数组定义，并循环

String data[] = new String[] {"sss","kejin","laowan"};
		for (String i : data) {
	        System.out.println(i);

str.substring(4);
切割前四个字符，保留后面的
str.substring(4,5);
切割前四个字符，切割后四个字符保留剩下的

map的使用（存放键值对）

Map m1 = new HashMap<K, V>();
		m1.put("name","aaa");
		m1.put(2,"bbb");
		
		
		System.out.println(m1.get("name"));
		System.out.println(m1.size());

动态数组

public class array1 {
public static void main(String[] args) {
	

	int[] a=new int[11];
	
	for (int i = 0; i < 11; i++) {
		a[i]=i*5;
	}
	
	
	a[10]=100;
	
	System.out.println("**************");
	for (int m:a) {
		
		System.out.println(m);
	}
}		
}


二维数组

```c
public class array2 {
public static void main(String[] args) {
	

	int[][] a=new int[4][4];
	
	
	
	
	a[3][3]=100;
	
	for (int j = 0; j <= 3; j++) {
		for (int k = 0; k<=3; k++) {
			a[j][k]=1;
		}
	}
	a[3][3]=100;
	
						for (int i = 0; i <=3; i++) {
							for (int m = 0; m <=3; m++) {
								System.out.print(    a[i][m] +"\t"  );
							}
							System.out.println(" ");
						}	
}	
	
}