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Enhancement
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Resolution: Duplicate
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P5
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None
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1.1
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generic
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generic
CardLayout.add(Component) throws an exception "Illegal argument".
The sample code works on 1.0.2 but 1.1.
import java.awt.*;
import java.util.*;
import java.io.*;
import java.net.*;
import java.applet.*;
import java.lang.*;
public class Test extends Applet {
Panel cardPanel;
public void init() {
Panel panel;
cardPanel = new Panel();
cardPanel.setLayout( new CardLayout(10,10));
cardPanel.add( new Button( "card first"));
cardPanel.add( new Button( "card second" ));
cardPanel.add( new Button( "card third" ));
cardPanel.add( new Button( "card fourth" ));
cardPanel.add( new Button( "card fifth" ));
add( cardPanel );
resize( 300, 400 );
show();
}
public boolean action(Event e, Object o) {
((CardLayout)cardPanel.getLayout()).next( cardPanel );
return true;
}
}
<!DOCTYPE HTML PUBLIC "-//SQ//DTD HTML 2.0 HoTMetaL + extensions//EN">
<HTML><HEAD><TITLE>Listing 5-1: Using LayoutManagers</TITLE></HEAD>
<BODY>
<applet code="Test.class" height=100 width=100>
</applet>
</BODY></HTML>
~
~
Result:
appletviewer Test.html
java.lang.IllegalArgumentException: cannot add to layout: constraint must be a string
at java.awt.CardLayout.addLayoutComponent(CardLayout.java:100)
at java.awt.Container.addImpl(Container.java)
at java.awt.Container.add(Container.java)
at Test.init(Test.java:15)
at sun.applet.AppletPanel.run(AppletPanel.java:273)
at java.lang.Thread.run(Thread.java)
add method in Container.java passes "null" as constraints as shown below
/**
* Adds the specified component to this container.
* @param comp the component to be added
*/
public Component add(Component comp) {
addImpl(comp, null, -1);
return comp;
}
while addLayoutComponent in CardLayout.java checks if constraints is
an instance of String as shown below.
public void addLayoutComponent(Component comp, Object constraints) {
if (constraints instanceof String) {
addLayoutComponent((String)constraints, comp);
} else {
throw new IllegalArgumentException("cannot add to layout: constraint
must be a string");
}
The sample code works on 1.0.2 but 1.1.
import java.awt.*;
import java.util.*;
import java.io.*;
import java.net.*;
import java.applet.*;
import java.lang.*;
public class Test extends Applet {
Panel cardPanel;
public void init() {
Panel panel;
cardPanel = new Panel();
cardPanel.setLayout( new CardLayout(10,10));
cardPanel.add( new Button( "card first"));
cardPanel.add( new Button( "card second" ));
cardPanel.add( new Button( "card third" ));
cardPanel.add( new Button( "card fourth" ));
cardPanel.add( new Button( "card fifth" ));
add( cardPanel );
resize( 300, 400 );
show();
}
public boolean action(Event e, Object o) {
((CardLayout)cardPanel.getLayout()).next( cardPanel );
return true;
}
}
<!DOCTYPE HTML PUBLIC "-//SQ//DTD HTML 2.0 HoTMetaL + extensions//EN">
<HTML><HEAD><TITLE>Listing 5-1: Using LayoutManagers</TITLE></HEAD>
<BODY>
<applet code="Test.class" height=100 width=100>
</applet>
</BODY></HTML>
~
~
Result:
appletviewer Test.html
java.lang.IllegalArgumentException: cannot add to layout: constraint must be a string
at java.awt.CardLayout.addLayoutComponent(CardLayout.java:100)
at java.awt.Container.addImpl(Container.java)
at java.awt.Container.add(Container.java)
at Test.init(Test.java:15)
at sun.applet.AppletPanel.run(AppletPanel.java:273)
at java.lang.Thread.run(Thread.java)
add method in Container.java passes "null" as constraints as shown below
/**
* Adds the specified component to this container.
* @param comp the component to be added
*/
public Component add(Component comp) {
addImpl(comp, null, -1);
return comp;
}
while addLayoutComponent in CardLayout.java checks if constraints is
an instance of String as shown below.
public void addLayoutComponent(Component comp, Object constraints) {
if (constraints instanceof String) {
addLayoutComponent((String)constraints, comp);
} else {
throw new IllegalArgumentException("cannot add to layout: constraint
must be a string");
}
- duplicates
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JDK-4029317 Exception when adding a component to a panel with CardLayout
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- Closed
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