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NullPointerException: Rendering screen


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Sometimes, when I open my customGui, the server shuts down and shows this error:


at net.minecraft.client.gui.GuiScreen.drawWorldBackground(GuiScreen.java:396)
at net.minecraft.client.gui.GuiScreen.drawDefaultBackground(GuiScreen.java:391)
at com.guje.test_mod.TestBlockGui.drawScreen(TestBlockGui.java:71)

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In line 71 there is only




rest of the class:

package com.guje.test_mod;

import org.lwjgl.opengl.GL11;

import net.minecraft.block.Block;
import net.minecraft.client.gui.GuiButton;
import net.minecraft.client.gui.GuiScreen;
import net.minecraft.client.gui.GuiTextField;
import net.minecraft.util.ResourceLocation;
import net.minecraft.world.World;

public class TestBlockGui extends GuiScreen {

private int textureX;
private int textureY;
private int posY;
private int posX;
private int bY;
private int bX;
private int bZ;
private ResourceLocation texture;
private World world;
private String blockId;
private String blockMetadata;
private GuiTextField text_BlockId;
private GuiTextField text_BlockMetadata;

public TestBlockGui(Block block, World world, int bX, int bY, int bZ) {
	this.textureX = 175;
	this.textureY = 221;
	this.bX = bX;
	this.bY = bY;
	this.bZ = bZ;
	this.world = world;
	this.blockId = block.getIdFromBlock(block)+"";
	this.blockMetadata = world.getBlockMetadata(bX, bY, bZ)+"";
	texture = new ResourceLocation(Hack_n_Mine.MODID, "textures/gui/hackingGui.png");

public void initGui() {
	posX = (this.width - textureX) / 2;
	posY = (this.height - textureY) / 2;
	text_BlockId = new GuiTextField(fontRendererObj, posX + 77, posY + 5, 40, 10);
	text_BlockMetadata = new GuiTextField(fontRendererObj, posX + 77, posY + 18, 40, 10);

protected void keyTyped(char c, int i) {
	text_BlockId.textboxKeyTyped(c, i);
	text_BlockMetadata.textboxKeyTyped(c, i);
	super.keyTyped(c, i);

protected void mouseClicked(int i, int j, int f) {
	text_BlockId.mouseClicked(i, j, f);
	text_BlockMetadata.mouseClicked(i, j, f);
	super.mouseClicked(i, j, f);

public void drawScreen(int x, int y, float f) {
	posX = (this.width - textureX) / 2;
	posY = (this.height - textureY) / 2;

	drawTexturedModalRect(posX, posY, 0, 0, textureX, textureY);
	fontRendererObj.drawString("BlockID", posX + 5, posY + 7, 0x404040);
	fontRendererObj.drawString("BlockMetadata", posX + 5, posY + 19, 0x404040);
	super.drawScreen(x, y, f);

public void onGuiClosed() {
	//Set blockId and metadata
	Block b = Block.getBlockById(Integer.parseInt(text_BlockId.getText()));
	int m = Integer.parseInt(text_BlockMetadata.getText());
	world.setBlock(bX, bY, bZ, b, m, 3);


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in this function


    public boolean onItemUse(ItemStack item, EntityPlayer player,
    		World world, int x, int y, int z,
    		int par7, float xFloat, float yFloat,
    		float zFloat) {
    	if (!player.canPlayerEdit(x, y, z, par7, item)){
    		return false;
    	if (!world.isRemote){
    		Block target = world.getBlock(x, y, z);
    		Minecraft.getMinecraft().displayGuiScreen(new TestBlockGui(target,world,x,y,z));
    	return true;

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    	if (!world.isRemote){
    		Block target = world.getBlock(x, y, z);
    		Minecraft.getMinecraft().displayGuiScreen(new TestBlockGui(target,world,x,y,z));


You're checking to see if it's on the server side, isRemote returns true for client and false for servers. Minecraft is a client only class.

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