[英]Null Pointer Exception not caught in java dialogue
我正在嘗試從 java 對話框接收輸入,並且在關閉框時我似乎無法捕獲NullPointerException
,有人可以幫忙嗎?
private static final String DEFAULTNAME = "Player001";
public class Player implements Serializable
{
private String name;
private int score;
public Player(String Pname,int Pscore)
{
name = Pname;
score = Pscore;
}
}
try
{
person = new Player(JOptionPane.showInputDialog("Please enter your name"),0);
}
catch(NullPointerException e)
{
person = new Player(DEFAULTNAME,0);
}
catch(Throwable t)
{
person = new Player(DEFAULTNAME,0);
}
有沒有人有解決方案或者有沒有辦法讓對話框無法關閉?
你不會像你正在做的那樣“抓住”一個 NPE。 從用戶那里獲取String,看是否== null,如果是則使用默認播放器名稱。 在偽代碼中:
call JOptionPane and get player name
If player name is null
create new Player with default name
else
create new Player with the user-entered name.
這里不需要嘗試/捕獲。
另一種解決方法是讓您的 Player 構造函數接受 null 字符串並將其更改為默認值:
public Player(String Pname,int Pscore)
{
name = (Pname == null || Pname.trim().isEmpty()) ? DEFAULT_NAME : Pname;
score = Pscore;
}
您最好在添加之前檢查名稱中的無效值
String name = JOptionPane.showInputDialog("Please enter your name");
if(name == null || name.equals(""))name = DEFAULTNAME;
person = new Player(name,0);
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