在ie(sun java plugin1.4.2_07)中运行: java.lang.NullPointerException at java.awt.Container.addImpl(Unknown Source) at java.awt.Container.add(Unknown Source) at Applet1.init(Applet1.java:13) at sun.applet.AppletPanel.run(Unknown Source) at java.lang.Thread.run(Unknown Source)Opera中(同一个jre) java.lang.NullPointerException at java.awt.Container.addImpl(Unknown Source) at java.awt.Container.add(Unknown Source) at Applet1.init(Applet1.java:13) at com.opera.PluginPanel.run(PluginPanel.java:426) at java.lang.Thread.run(Unknown Source)Mozilla Firefox中 java.lang.NullPointerException at java.awt.Container.addImpl(Unknown Source) at java.awt.Container.add(Unknown Source) at Applet1.init(Applet1.java:13) at sun.applet.AppletPanel.run(Unknown Source) at java.lang.Thread.run(Unknown Source)好像不是你的问题,那是什么问题呢????
当然是他自己的问题喽, 用 Checkbox checkbox1[]=new Checkbox[50]; 这一句只是分配了一个包含50个null的空数组,使用数组中的元素之前还需要初始化其中的元素。for (int t = 0; t < checkbox1.length; t++) { checkbox1[t] = new Checkbox(); }
java.lang.NullPointerException
at java.awt.Container.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at Applet1.init(Applet1.java:13)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)Opera中(同一个jre)
java.lang.NullPointerException
at java.awt.Container.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at Applet1.init(Applet1.java:13)
at com.opera.PluginPanel.run(PluginPanel.java:426)
at java.lang.Thread.run(Unknown Source)Mozilla Firefox中
java.lang.NullPointerException
at java.awt.Container.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at Applet1.init(Applet1.java:13)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)好像不是你的问题,那是什么问题呢????
用 Checkbox checkbox1[]=new Checkbox[50]; 这一句只是分配了一个包含50个null的空数组,使用数组中的元素之前还需要初始化其中的元素。for (int t = 0; t < checkbox1.length; t++)
{
checkbox1[t] = new Checkbox();
}
只是那些checkbox会先显示在画面上,而不是按下按钮后才显示出来.