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cannot add to layout: constraint mu be a string (or null)
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cannot add to layout: constraint must be a string (or null)
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cannot add to layout: constraint must be a string (or null)
via Oracle Community by 843804, 2 years ago
cannot add to layout: constraint must be a string (or null)
java.lang.IllegalArgumentException: cannot add to layout: constraint mu
be a string (or null)	at java.awt.BorderLayout.addLayoutComponent(BorderLayout.java:401)	at javax.swing.JRootPane$1.addLayoutComponent(JRootPane.java:453)	at java.awt.Container.addImpl(Container.java:482)	at java.awt.Container.add(Container.java:345)	at eMailFrame.add(eMail.java:118)	at eMailFrame.(eMail.java:67)	at eMail.main(eMail.java:12)