水平对齐问题

Question

我想在面板中央放置一些按钮，但不起作用。在这里我的代码：

import com.extjs.gxt.ui.client.widget.HorizontalPanel; 
import com.extjs.gxt.ui.client.widget.Label; 
import com.extjs.gxt.ui.client.widget.LayoutContainer; 
import com.extjs.gxt.ui.client.widget.VerticalPanel; 
import com.extjs.gxt.ui.client.widget.button.Button; 
import com.google.gwt.core.client.EntryPoint; 
import com.google.gwt.user.client.ui.HasAlignment; 
import com.google.gwt.user.client.ui.RootPanel; 

private void addStartupBox() { 
    VerticalPanel boxPanel = setBoxSize();  
    com.google.gwt.user.client.ui.Label title = createBoxTitle("Prüfungen");   

    // Create second panel for the content of a box  
    com.google.gwt.user.client.ui.VerticalPanel boxContent = new com.google.gwt.user.client.ui.VerticalPanel(); 
    boxContent.setSpacing(10); 
    boxContent.setHorizontalAlignment(com.google.gwt.user.client.ui.VerticalPanel.ALIGN_CENTER); 

    // Create content for the box 
    Button but1 = new Button("A"); 
    but1.setPixelSize(280, 25);  

    Button but2 = new Button("B"); 
    but2.setPixelSize(280, 25); 

    Button but3 = new Button("C"); 
    but3.setPixelSize(280, 25); 

    // Add buttons to boxContent 
    boxContent.add(but1); 
    boxContent.add(but2); 
    boxContent.add(but3); 

    // Add title and boxContent to boxPanel  
    boxPanel.add(title); 
    boxPanel.add(boxContent); 

    RootPanel.get("boxPanelContainer").add(boxPanel); 
} 

结果是：

here http://tinyurl.com/ycs2q4o

并且按钮左对齐。之后我尝试了这种方式：

boxContent.setHorizontalAlignment(HasAlignment.ALIGN_CENTER); 

但是按钮仍左对齐。我最后的想法是使用ExtGWT垂直面板与此：

boxContent.setHorizontalAlign(HorizontalAlignment.CENTER); 

但不幸的是也不起作用。有人可以告诉我，我做错了什么？

Answer 1

问题解决了....我添加了另一个面板，左对齐。这里的代码：

private void addStartupBox() { 
    VerticalPanel boxPanel = setBoxSize();  
    com.google.gwt.user.client.ui.Label title = createBoxTitle("Prüfungen");   
    boxPanel.setHorizontalAlign(HorizontalAlignment.CENTER); 

    // Create second panel for the content of a box  
    com.google.gwt.user.client.ui.VerticalPanel boxContent = new com.google.gwt.user.client.ui.VerticalPanel(); 
    boxContent.setSpacing(10); 

    // Create third panel, which contains the label 
    VerticalPanel labelPanel = new VerticalPanel(); 
    labelPanel.setHorizontalAlign(HorizontalAlignment.LEFT);   

    // Create content for the box 
    Button but1 = new Button("A"); 
    but1.setPixelSize(280, 25);  

    Button but2 = new Button("B"); 
    but2.setPixelSize(280, 25); 

    Button but3 = new Button("C"); 
    but3.setPixelSize(280, 25); 

    // Add buttons to boxContent 
    boxContent.add(but1); 
    boxContent.add(but2); 
    boxContent.add(but3); 

    // Add title to third panel 
    labelPanel.add(title);  

    // Add title and boxContent to boxPanel 
    boxPanel.add(labelPanel); 
    boxPanel.add(boxContent); 

    RootPanel.get("boxPanelContainer").add(boxPanel); 
} 

Answer 2

添加以下代码，并尝试后的按钮添加到框的内容（“RootPanel.get（” boxPanelContainer前

boxContent.setCellHorizontalAlignment(but1, HasHorizontalAlignment.ALIGN_CENTER); 
boxContent.setCellHorizontalAlignment(but2, HasHorizontalAlignment.ALIGN_CENTER); 
boxContent.setCellHorizontalAlignment(but3, HasHorizontalAlignment.ALIGN_CENTER); 

上面的代码应该添加“）添加（boxPanel）;”这行）。