我的日食檢測到錯誤

Question

什麼錯我的我的一個FileFilter說，它的傾斜istantiate

import javax.swing.*; 
import javax.swing.filechooser.FileFilter; 

import java.io.File;  

public class fileChooser2 extends Object { 
public fileChooser2() { 
JFileChooser chooser = new JFileChooser(); 
    // Note: source for ExampleFileFilter can be found in FileChooserDemo, 
    // under the demo/jfc directory in the JDK. 
    FileFilter filter = new FileFilter(); 
    filter.addExtension("jpg"); 
    filter.addExtension("gif"); 
    filter.setDescription("JPG & GIF Images"); 
    chooser.setFileFilter(filter); 
    int returnVal = chooser.showOpenDialog(parent); 
    if(returnVal == JFileChooser.APPROVE_OPTION) { 
     System.out.println("You chose to open this file: " + 
      chooser.getSelectedFile().getName()); 


} 
} 
} 

Answer 1

FileFilter是abstract類（這意味着它不能被實例化），必須擴展它。有關FileFilter的具體實現，請參閱FileNameExtensionFilter。您可能還想看tutorial on how to use FileChoosers which has a section on custom FileFilters

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如果使用FileNameExtensionFilter，你可以改變這個

FileFilter filter = new FileFilter(); 
filter.addExtension("jpg"); 
filter.addExtension("gif"); 
filter.setDescription("JPG & GIF Images"); 

這個

FileNameExtensionFilter filter = new FileNameExtensionFilter("JPG & GIF Images", "jpg", "gif");