如何复制二维字符串数组？

Question

I'm having difficulty copying string array values into a new string array.

For example:

String[][] array = new String[3][2];
array[0][0] = "hello";
array[0][1] = "1";
array[1][0] = "guys";
array[1][1] = "2";
array[2][0] = "good ";
array[2][1] = "3";

array = new String [5][2];
all the value in the first array to be copied
array[3][0] = "";
array........;

I tried this method but it keeps me giving null pointer issues whenever I want to insert a new value.

String[][] array = new String[3][2];
array[0][0] = "olo";
array[0][1] = "ada ";
array[1][0] = "apa";
array[1][1] = "dengan";
array[2][0] = "si ";
array[2][1] = "carlo";


String[][] newArray = new String[5][2];
newArray = Arrays.copyOf(array, 5);
array = new String[5][2];
array = Arrays.copyOf(newArray, 5);
array[3][0] = "lo";
array[3][1] = "gw";
array[4][0] = "end";
array[4][1] = "ennnnnd";

for (int r = 0; r < array.length; r++) {
    for (int c = 0; c < array[r].length; c++) {
        System.out.print(" " + array[r][c]);
    }
    System.out.println("");
}

How can I copy this 2d string array?

Answer 1

Java has a built in function called arraycopy that can do this for you without a double for loop. Much more efficient.

Answer 2

First of all the newer array has more elements that source array so decide what you want to do about it. Also if old array is called array call the new array by a different name say newarray .

for ( int i = 0; i < 3; ++i )
{
  for( int j = 0; j < 2; ++i )
  {
      newarray[i][j] = array[i][j];
  }
}

Answer 3

您可以使用 Arrays.copyOfRange(String param, fromIndex, toIndex)