Almost works, Display at 7 works, doesn't stop when finishing / print solution

src/part5/aufg2/Demo.java

@@ -3,10 +3,12 @@ package part5.aufg2;
 public class Demo {
     public static void main(String[] args) {
         Queenproblem Q = new Queenproblem();
-        System.out.println(Q.field[2]);
+        Q.setField(new int[]{0, 0, 0, 0, 0, 0, 0, 0});
-        Q.setField(new int[] {0,0,2,3,4,5,0,0});
         Q.print();
+        System.out.println("=============");
+        Q.solve(0);
 
         }
     }
 
+

src/part5/aufg2/Queenproblem.java

@@ -25,9 +25,10 @@ public class Queenproblem {
         for (int i=0; i<8; i++) {
             try {
                 int yPosition = this.field[i];
-                field[i][yPosition-1] = 1;   // -1 to handle 0 as empty and 8 as lowest possible with actual index 7
+                field[yPosition-1][i] = 1;   // -1 to handle 0 as empty and 8 as lowest possible with actual index 7
             }catch (IndexOutOfBoundsException e){
-                System.out.println("Ignored Index Error while making it 2D");
+                ;
+                //System.out.println("Ignored Index Error while making it 2D");
             }
         }
 
@@ -39,6 +40,7 @@ public class Queenproblem {
         for (int[] row:field) {
             System.out.println(Arrays.toString(row));
         }
+        System.out.println();
     }
 
     public boolean checkVertical(int col){
@@ -48,37 +50,116 @@ public class Queenproblem {
         return true;
     }
 
-    public boolean checkHorizontal(int col){
+    public boolean checkHorizontal(int row){
         for (int colFilled : this.field) {
-            if (colFilled == col){
+            if (colFilled == row){
                 return false;
             }
         }
         return true;
     }
 
-    public boolean isPossible(int row, int col){
+    private void ensureLegalCords(int row, int col){
-        int x = --row;
+        if (col<1 || col>8){
-        int y = --col;
+            throw new RuntimeException("Invalid Col " + col);
+        }
+        if (row<1 || row>8){
+            throw new RuntimeException("Invalid Row " + row);
+        }
+    }
+    public boolean checkFallingDiagonal(int row, int col){
+        ensureLegalCords(row, col);
 
-        // Vertical
-        if (this.field[x] != 0)
-            return false;
-
-        // Diagonal \
         for (int i = 0; i < 8; i++) {
             try {
-                if (this.field[x+i] == y+i){
+                if (this.field[col-1+i] != 0) {
+                    if (this.field[col - 1 + i] == row + i) {
                         return false;
                     }
-                if (this.field[x-i] == y-i){
-                    return false;
                 }
             }catch (IndexOutOfBoundsException e){
-                System.out.println("Ignored index Error with Diagonal Possibility Check");
+                ; // Skip Iteration with IndexError
-            }
             }
 
+            // cannot be in the same try block.
+            // Exceptions in the + direction stop execution of - prematurely
+            try {
+                if (this.field[col-1-i] != 0) {
+                    if (this.field[col - 1 - i] == row - i) {
+                        return false;
+                    }
+                }
+            }catch (IndexOutOfBoundsException e){
+                ; // Skip Iteration with IndexError
+            }
+        }
         return true;
     }
+
+    public boolean checkRisingDiagonal(int row, int col){
+        ensureLegalCords(row, col);
+
+        for (int i = 0; i < 8; i++) {
+            try {
+                if (this.field[col-1+i] != 0) {
+                    if (this.field[col - 1 + i] == row - i) {
+                        return false;
+                    }
+                }
+            }catch (IndexOutOfBoundsException e){
+                ;
+            }
+            try {
+                if (this.field[col-1-1] != 0) {
+                    if (this.field[col - 1 - i] == row + 1) {
+                        return false;
+                    }
+                }
+            }catch (IndexOutOfBoundsException e){
+                ;
+            }
+        }
+        return true;
+    }
+    public boolean isPossible(int row, int col){
+
+        if(checkHorizontal(row) == false){
+            return false;
+        }
+
+        if (checkVertical(col) == false) {
+            return false;
+        }
+
+        // Diagonal \
+        if (checkFallingDiagonal(row, col) == false){
+            return false;
+        }
+
+
+        if (checkRisingDiagonal(row, col) == false){
+            return false;
+        }
+        return true;
+    }
+
+    public void solve(int queensPlaced){
+        if (queensPlaced == 7){
+            this.print();
+        }
+        for (int col = 1; col < 9; col++) {
+            if (this.field[col-1] == 0) {
+                for (int row = 1; row < 9; row++) {
+                    if (isPossible(row,col)) {
+                        this.field[col-1] = row;
+                        queensPlaced++;
+                        this.solve(queensPlaced);
+                        queensPlaced--;
+                        this.field[col-1] = 0;
+                    }
+                }
+                return;
+            }
+        }
+    }
 }