Cannot be resolved to a variable

Question

What means can not be resolved to a variable? The condition contains an action that creates the variable Double xco, which is equal to the difference in the coordinates of the players by the "x". In another condition, I call this variable: "If_ (xco <10) {...}" At this stage, an error is generated

@EventHandler public <ChatMessage> void onPlayerChat(AsyncPlayerChatEvent z) { Player p=z.getPlayer(); Location I=p.getLocation(); String a=z.getMessage(); if (a.equals("word")) { for (Player ps : Bukkit.getOnlinePlayers()) { Location i = ps.getLocation(); if (I.getX()<0 && i.getX()<0){ double xco = I.getX() - i.getX();} else if (I.getX()>0 && i.getX()>0 ) { double xco = I.getX() - i.getX();} if (I.getY()<0 && i.getY()<0) { double yco = I.getY() - i.getY();} else if (I.getY()>0 && i.getY()>0 ) { double yco = I.getY() - i.getY();} if (I.getZ()<0 && i.getZ()<0) { double zco = I.getZ() - i.getZ();} else if (I.getZ()>0 && i.getZ()>0 ) { double zco = I.getZ() - i.getZ();} if (xco<10) { ps.playSound(ps.getLocation(), Sound.BLOCK_ANVIL_DESTROY, 1, 5); ps.sendMessage("Test");}

It is not recommended to create variables "in condition". This leads to such errors. - Enikeyschik

Enikeyshchik Enikeyshchik 7,028 five 9 27 · Accepted Answer · 2019-04-28T11:27:57

Variables must be created at the beginning of the class / method where they are used. First, they are then available throughout the class / method, and secondly, it makes reading and understanding the code easier:

 public <ChatMessage> void onPlayerChat(AsyncPlayerChatEvent z) { Player p = z.getPlayer(); Location I = p.getLocation(); String a = z.getMessage(); double xco = 0; // <- вот здесь double yco = 0; double zco = 0;

In your code, the xco variable may not be created at all, which will cause the program to crash during execution.

If this is overwritten, then Duplicate local variable errors occur under the conditions where they were given values
Because in the future you just need to write xco , not double xco .
2. What happens if I.getX() greater than 0 and i.getX() less than 0?

Cannot be resolved to a variable

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