🎃(array): 463. 岛屿的周长 add java code

Author: csming1995

docs/data-structure/array/README.md

@@ -1732,6 +1732,31 @@ func islandPerimeter(grid [][]int) int {
 }
 ```
 
+#### **Java**
+
+```java
+class Solution {
+    public int islandPerimeter(int[][] grid) {
+        if (grid == null || grid.length <= 0 || grid[0] == null || grid[0].length <= 0) return 0;
+        int height = grid.length;
+        int width = grid[0].length;
+
+        int result = 0;
+
+        for (int i = 0; i < height; i++) {
+            for (int j = 0; j < width; j++) {
+                if (grid[i][j] == 1) {
+                    if (i == 0 || grid[i - 1][j] == 0) result++;
+                    if (j == 0 || grid[i][j - 1] == 0) result++;
+                }
+            }
+        }
+
+        return result * 2;
+    }
+}
+```
+
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 ## 485. 最大连续1的个数