[1.10.2] Eclipse error "The method isEmpty() is undefined for the type ItemStack"

[Tortuga]

Quote

package tortuga.primeiro.entity;

import net.minecraft.entity.ai.EntityAIAvoidEntity;
import net.minecraft.entity.ai.EntityAINearestAttackableTarget;
import net.minecraft.entity.monster.EntityCreeper;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.world.World;

import javax.annotation.Nullable;

/**
 * A creeper that avoids players holding an item in their off hand.
 * <p>
 * Test for this thread:
 * http://www.minecraftforum.net/forums/mapping-and-modding/minecraft-mods/modification-development/2782263-how-to-make-a-creeper-avoid-certain-players
 *
 * @author Choonster
 */
public class EntityPlayerAvoidingCreeper extends EntityCreeper {
    public EntityPlayerAvoidingCreeper(final World worldIn) {
        super(worldIn);
    }

    @Override
    protected void initEntityAI() {
        super.initEntityAI();

        // Remove the EntityAINearestAttackableTarget task added by EntityCreeper so it can be replaced
        targetTasks.taskEntries.stream()
                .filter(taskEntry -> taskEntry.action instanceof EntityAINearestAttackableTarget)
                .findFirst()
                .ifPresent(taskEntry -> targetTasks.removeTask(taskEntry.action));

        // Avoid players if they have an item in their off hand
        tasks.addTask(3, new EntityAIAvoidEntity<>(this, EntityPlayer.class, this::shouldAvoidPlayer, 6.0F, 1.0D, 1.2D));

        // Only attack players without an item in their off hand
        targetTasks.addTask(1, new EntityAINearestAttackableTarget<>(this, EntityPlayer.class, 10, true, false, (player) -> !shouldAvoidPlayer(player)));
    }

    /**
     * Should this creeper avoid the specified player?
     *
     * @param player The player
     * @return True if the player has an item in their off hand
     */
    private boolean shouldAvoidPlayer(@Nullable final EntityPlayer player) {
        return player != null && !player.getHeldItemOffhand().isEmpty();
    }
}

I was trying to add a mob from an example that I found, but I gets this error. Is there anyone who could help me? I would be glad

Edited December 22, 2017 by Tortuga

[Tortuga]

dieseben07 Thank you for helping, I'm new at modding so I don't understand much about it, but thx for your help

[Tortuga]

9 minutes ago, diesieben07 said:

• Do not blindly copy examples that you find. You must understand the code to use it properly.
• ItemStack::isEmpty is a method that was added in 1.11.x. Stop using 1.10.x.

Thank you for helping, I'm new at modding so I don't understand much about it, but thx for your help