05 - JavaSE之数组

int[] a = new int[5];

int a[];
a = new int[3];
a[0] = 1;
a[1] = 2;
a[2] = 3;

int a[] = {1, 2, 3};
Date days[] = {
    new Date(1, 4, 2004);
    new Date(2, 4, 2004);
    new Date(3, 4, 2004);
}

int a[] = new int[3];
Date days = new Date[3];
// 则a中元素值为0；days中的元素值为null

// 例如
int a[][] = new int [3][];
a[0] = new int[3];
a[1] = new int[4];
a[2] = new int[5];
// int t[][] = new int[][3]; // 错误

int A[][] = {{1,2}, {3,4}, {5,6,7}};
// 错误 int B[3][2] = {{1,2}, {3,4}, {5,6}}; 
// 错误 int B[][2] = {{1,2}, {3,4}, {5,6}}; 
// 错误 int B[3][] = {{1,2}, {3,4}, {5,6}}; 

int a[][] = new int[2][3];
// 或者

int b[][] = new int[2][];
b[0] = new int[3];
b[1] = new int[4];

public static void arraycopy(Object src, int srcPos, Object dest, int destPos, int length)

public class TestArrayCopy {
  public static void main(String args[]) {
    String[] s = 
            {"Mircosoft","IBM","Sun","Oracle","Apple"};
    String[] sBak = new String[6];
    System.arraycopy(s,0,sBak,0,s.length);
    
    for(int i=0;i<sBak.length;i++){
      System.out.print(sBak[i]+" ");
    }
    
    System.out.println();
    int[][] intArray = {{1,2},{1,2,3},{3,4}};
    int[][] intArrayBak = new int[3][];
    System.arraycopy
            (intArray,0,intArrayBak,0,intArray.length);
    intArrayBak[2][1] = 100;
    
    for(int i = 0;i<intArray.length;i++){
        for(int j =0;j<intArray[i].length;j++){
            System.out.print(intArray[i][j]+"  "); 
        }
        System.out.println();
    }
  }
}