base java functionality

java/Cell.java

@@ -0,0 +1,52 @@
+import java.util.BitSet;
+
+public class Cell {
+    private BitSet candidates = new BitSet(9);
+    private Cell[] row;
+    private Cell[] col;
+    private Cell[] square;
+    public final int pos;
+    private int n_set;
+
+    public Cell(int pos) {
+        this.candidates.set(0, 9);
+        this.n_set = 9;
+        this.pos = pos;
+    }
+
+    public void finishInit(Cell[] row, Cell[] col, Cell[] square) {
+        this.row = row;
+        this.col = col;
+        this.square = square;
+    }
+
+    public void set(int i) {
+        this.candidates.clear(0, 9);
+        this.candidates.set(i-1);
+        this.n_set = 1;
+
+        for (Cell cell: this.row) {
+            cell.clear(i);
+        }
+        for (Cell cell: this.col) {
+            cell.clear(i);
+        }
+        for (Cell cell: this.square) {
+            cell.clear(i);
+        }
+    }
+
+    public void clear(int i) {
+        this.candidates.clear(i-1);
+        this.n_set -= 1;
+    }
+
+    public boolean probe(int i) {
+        return candidates.get(i-1);
+    }
+
+    public boolean getIsSet() {
+        return this.n_set == 1;
+    }
+}
+