Java FX 文本数组未初始化

Question

我正在使用 Java FX，我正在制作文本对象数组以在我的 GUI 上的不同点显示文本。我声明数组如下：

public Text[] texts = new Text[10];

在我的 start() 方法的最开始，我尝试将所有文本设为空白，如下所示：

for (Text text : texts) 
    text.setText("");

但是当我运行这样做时，我得到以下错误：

Exception in Application start method
java.lang.reflect.InvocationTargetException
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:473)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:372)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:941)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:973)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication(LauncherImpl.java:198)
    at java.base/java.lang.Thread.run(Thread.java:844)
Caused by: java.lang.NullPointerException
    at sample.Main.start(Main.java:93)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1(LauncherImpl.java:919)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait(PlatformImpl.java:449)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater(PlatformImpl.java:418)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater(PlatformImpl.java:417)
    at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop(WinApplication.java:175)
    ... 1 more
Exception running application sample.Main

上面我引用文本数组的 for 循环位于第 93 行。我认为编译器认为该数组为空（因此出现空指针异常）。有解决这个问题的简单方法吗？

提前致谢！

Answer 1

这是因为您的数组只包含空值。您需要使用文本对象填充数组。

public Text[] texts = new Text[10];
for(int i=0; i<texts.length; i++){
  texts[i] = new Text();
  texts[i].setText("");
}

下面将导致数组在使用前被初始化。

    public Text[] texts = { new Text(""), new Text(""),
                            new Text(""), new Text(""), 
                            new Text(""), new Text(""), 
                            new Text(""), new Text(""), 
                            new Text(""), new Text(""), };

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