java.lang.IllegalArgumentException

cannot add to layout: constraint mu be a string (or null)

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Solutions on the web21351

  • via Oracle Community by 807554, 11 months ago
    cannot add to layout: constraint mu be a string (or null)
  • cannot add to layout: constraint must be a string (or null)
  • cannot add to layout: constraint must be a string (or null)
  • Stack trace

    • 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.<init>(eMail.java:67) at eMail.main(eMail.java:12)

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