feat: binary-search java solution

Update binary-search.md

Author: azl397985856

91/binary-search.md

@@ -544,6 +544,24 @@ def bisect_left(A, x):
     return l
 ```
 
+##### Java
+
+```java
+import java.util.*;
+public class BinarySearch {
+    public int getPos(int[] A, int val) {
+        int low=0,high=A.lenght-1;
+        while (low <= high){
+            int mid = (low + high)/2;
+            if (A[mid] >= val){
+                high = mid-1;
+            }else low = mid+1;
+        }
+        return low;
+    }
+}
+```
+
 其他语言暂时空缺，欢迎
 [PR](https://github.com/azl397985856/leetcode-cheat/issues/4)