Implement basic getXX methods for JDBC4ResultSet

bindings/java/src/main/java/org/github/tursodatabase/core/LimboResultSet.java

@@ -117,6 +117,25 @@ public class LimboResultSet {
     this.open = false;
   }
 
+  // Note that columnIndex starts from 1
+  @Nullable
+  public Object get(int columnIndex) throws SQLException {
+    if (!this.isOpen()) {
+      throw new SQLException("ResultSet is not open");
+    }
+
+    if (this.lastStepResult == null || this.lastStepResult.getResult() == null) {
+      throw new SQLException("ResultSet is null");
+    }
+
+    final Object[] resultSet = this.lastStepResult.getResult();
+    if (columnIndex > resultSet.length) {
+      throw new SQLException("columnIndex out of bound");
+    }
+
+    return resultSet[columnIndex - 1];
+  }
+
   @Override
   public String toString() {
     return "LimboResultSet{"

bindings/java/src/main/java/org/github/tursodatabase/core/LimboStatement.java

@@ -55,6 +55,11 @@ public class LimboStatement {
     return result;
   }
 
+  /**
+   * Because Limbo supports async I/O, it is possible to return a {@link LimboStepResult} with
+   * {@link LimboStepResult#STEP_RESULT_ID_ROW}. However, this is handled by the native side, so you
+   * can expect that this method will not return a {@link LimboStepResult#STEP_RESULT_ID_ROW}.
+   */
   @Nullable
   private native LimboStepResult step(long stmtPointer) throws SQLException;
 

bindings/java/src/main/java/org/github/tursodatabase/core/LimboStepResult.java

@@ -47,6 +47,11 @@ public class LimboStepResult {
         || stepResultId == STEP_RESULT_ID_ERROR;
   }
 
+  @Nullable
+  public Object[] getResult() {
+    return result;
+  }
+
   @Override
   public String toString() {
     return "LimboStepResult{"

bindings/java/src/main/java/org/github/tursodatabase/jdbc4/JDBC4ResultSet.java

@@ -3,10 +3,26 @@ package org.github.tursodatabase.jdbc4;
 import java.io.InputStream;
 import java.io.Reader;
 import java.math.BigDecimal;
+import java.math.RoundingMode;
 import java.net.URL;
-import java.sql.*;
+import java.sql.Array;
+import java.sql.Blob;
+import java.sql.Clob;
+import java.sql.Date;
+import java.sql.NClob;
+import java.sql.Ref;
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.sql.RowId;
+import java.sql.SQLException;
+import java.sql.SQLWarning;
+import java.sql.SQLXML;
+import java.sql.Statement;
+import java.sql.Time;
+import java.sql.Timestamp;
 import java.util.Calendar;
 import java.util.Map;
+import org.github.tursodatabase.annotations.Nullable;
 import org.github.tursodatabase.annotations.SkipNullableCheck;
 import org.github.tursodatabase.core.LimboResultSet;
 
@@ -35,64 +51,99 @@ public class JDBC4ResultSet implements ResultSet {
   }
 
   @Override
+  @Nullable
   public String getString(int columnIndex) throws SQLException {
-    // TODO
-    return "";
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return null;
+    }
+    return wrapTypeConversion(() -> (String) result);
   }
 
   @Override
   public boolean getBoolean(int columnIndex) throws SQLException {
-    // TODO
-    return false;
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return false;
+    }
+    return wrapTypeConversion(() -> (Long) result != 0);
   }
 
   @Override
   public byte getByte(int columnIndex) throws SQLException {
-    // TODO
-    return 0;
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return 0;
+    }
+    return wrapTypeConversion(() -> ((Long) result).byteValue());
   }
 
   @Override
   public short getShort(int columnIndex) throws SQLException {
-    // TODO
-    return 0;
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return 0;
+    }
+    return wrapTypeConversion(() -> ((Long) result).shortValue());
   }
 
   @Override
   public int getInt(int columnIndex) throws SQLException {
-    // TODO
-    return 0;
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return 0;
+    }
+    return wrapTypeConversion(() -> ((Long) result).intValue());
   }
 
   @Override
   public long getLong(int columnIndex) throws SQLException {
-    // TODO
-    return 0;
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return 0;
+    }
+    return wrapTypeConversion(() -> (long) result);
   }
 
   @Override
   public float getFloat(int columnIndex) throws SQLException {
-    // TODO
-    return 0;
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return 0;
+    }
+    return wrapTypeConversion(() -> ((Double) result).floatValue());
   }
 
   @Override
   public double getDouble(int columnIndex) throws SQLException {
-    // TODO
-    return 0;
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return 0;
+    }
+    return wrapTypeConversion(() -> (double) result);
   }
 
+  // TODO: customize rounding mode?
   @Override
-  @SkipNullableCheck
+  @Nullable
   public BigDecimal getBigDecimal(int columnIndex, int scale) throws SQLException {
-    // TODO
-    return null;
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return null;
+    }
+    final double doubleResult = wrapTypeConversion(() -> (double) result);
+    final BigDecimal bigDecimalResult = BigDecimal.valueOf(doubleResult);
+    return bigDecimalResult.setScale(scale, RoundingMode.HALF_UP);
   }
 
   @Override
+  @Nullable
   public byte[] getBytes(int columnIndex) throws SQLException {
-    // TODO
-    return new byte[0];
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return null;
+    }
+    return wrapTypeConversion(() -> (byte[]) result);
   }
 
   @Override
@@ -300,10 +351,14 @@ public class JDBC4ResultSet implements ResultSet {
   }
 
   @Override
-  @SkipNullableCheck
+  @Nullable
   public BigDecimal getBigDecimal(int columnIndex) throws SQLException {
-    // TODO
-    return null;
+    final Object result = resultSet.get(columnIndex);
+    if (result == null) {
+      return null;
+    }
+    final double doubleResult = wrapTypeConversion(() -> (double) result);
+    return BigDecimal.valueOf(doubleResult);
   }
 
   @Override
@@ -1126,7 +1181,16 @@ public class JDBC4ResultSet implements ResultSet {
     return false;
   }
 
-  private SQLException throwNotSupportedException() {
-    return new SQLFeatureNotSupportedException("Not implemented by the driver");
+  @FunctionalInterface
+  public interface ResultSetSupplier<T> {
+    T get() throws Exception;
+  }
+
+  private <T> T wrapTypeConversion(ResultSetSupplier<T> supplier) throws SQLException {
+    try {
+      return supplier.get();
+    } catch (Exception e) {
+      throw new SQLException("Type conversion failed: " + e);
+    }
   }
 }