Question

我的编程类项目是创建一个程序（使用NetBeans），用户可以在其中输入电影信息并存储它。他们能够搜索电影列表以获取信息，即标题，演员，质量等。我有一个java文件，允许用户在文本字段中输入有关电影的信息，并将其保存到txt文件。

我遇到的问题是，每次用户搜索电影时，都会返回空指针异常。

以下是我搜索代码的一部分：

private void sbtnActionPerformed(java.awt.event.ActionEvent evt) {                                     
    try{
        if(!mField.getText().equals("Search Movie Title")){
            if(sameTitle(mField.getText())!=null){
                display_Search_Info.main(info);
                dispose();
            }else{
                JOptionPane.showMessageDialog(null, "No Movie Info Found.", "Error", JOptionPane.WARNING_MESSAGE);
            }
        }
        if(!aField.getText().equals("Search Actor Name")){
            if(sameActor(aField.getText())!=null){
                display_Search_Info.main(info);
                dispose();
            }else{
                JOptionPane.showMessageDialog(null, "No Movie Info Found.", "Error", JOptionPane.WARNING_MESSAGE);
            }
        }
        if(!gBox.getSelectedItem().equals("Select Genre")){
            if(sameGenre(String.valueOf(gBox.getSelectedItem()))!=null){
                display_Search_Info.main(info);
                dispose();
            }else{
                JOptionPane.showMessageDialog(null, "No Movie Info Found.", "Error", JOptionPane.WARNING_MESSAGE);
            }
        }
        if(!lBox.getSelectedItem().equals("Select Location")){
            if(sameLocation(String.valueOf(lBox.getSelectedItem()))!=null){
                display_Search_Info.main(info);
                dispose();
            }else{
                JOptionPane.showMessageDialog(null, "No Movie Info Found.", "Error", JOptionPane.WARNING_MESSAGE);
            }
        }
        if(mField.getText().equals("Search Movie Title")&&aField.getText().equals("Search Actor Name")&&gBox.getSelectedItem().equals("Select Genre")&&lBox.getSelectedItem().equals("Select Location")){
            JOptionPane.showMessageDialog(null, "Please Enter Information About The Movie", "Error", JOptionPane.WARNING_MESSAGE);                
        }
    }catch(IOException e){
        System.out.println("Error Occured");
    }    
}                                    
public String[] sameTitle(String s) throws IOException{
    BufferedReader br=new BufferedReader(new FileReader("M:/NetBeans Projects/MovieList/src/MovieInfo.txt"));
    String line;
    info= new String[6];
    do{
        for(int i=0; i<6; i++){
            info[i]=br.readLine();
        }
    }while((line=br.readLine())!=null);

    if(info[0].contains(s)){
        return info;
    }else{
        return null;
    }

}
public String[] sameActor(String s) throws IOException{
    BufferedReader br=new BufferedReader(new FileReader("M:/NetBeans Projects/MovieList/src/MovieInfo.txt"));
    String line="";
    info= new String[6];
    while((line=br.readLine())!=null&&!info[1].contains(s)||!info[2].contains(s)){
        for(int i=0; i<6; i++){
            info[i]=br.readLine();
        }
    }
    if(info[1].contains(s)||info[2].contains(s)){
        return info;
    }else{
        return null;
    }
}
public String[] sameGenre (String s) throws IOException{
    BufferedReader br=new BufferedReader(new FileReader("M:/NetBeans Projects/MovieList/src/MovieInfo.txt"));
    String line="";
    info= new String[6];
    while((line=br.readLine())!=null&&!info[3].contains(s)){
        for(int i=0; i<6; i++){
            info[i]=br.readLine();
        }
    }
    if(info[3].contains(s)){
        return info;
    }else{
        return null;
    }
}
public String[] sameLocation (String s) throws IOException{
    BufferedReader br=new BufferedReader(new FileReader("M:/NetBeans Projects/MovieList/src/MovieInfo.txt"));
    String line="";
    info= new String[6];
    while((line=br.readLine())!=null&&!info[4].contains(s)){
        for(int i=0; i<6; i++){
            info[i]=br.readLine();
        }
    }
    if(info[4].contains(s)){
        return info;
    }else{
        return null;
    }
}

jOptionPane不起作用，只是简单地将它发送到下一个文件 “线程中的异常”AWT-EventQueue-0“java.lang.NullPointerException”。

Answer 1

您的所有方法似乎都具有“相同”结构，我建议您使用List来存储匹配的行。也就是说，我认为你应该尝试更像这样的东西 -

public String[] sameLocation(String s) throws IOException {
    BufferedReader br = new BufferedReader(new FileReader(
            "M:/NetBeans Projects/MovieList/src/MovieInfo.txt"));
    String line = "";
    List<String> al = new ArrayList<String>();
    if (s != null) {
        while ((line = br.readLine()) != null) {
            for (int i = 0; i < 6; i++) { // <-- Why 6?
                al.add(line);
            }
        }
    }
    if (al.size() > 0) {
        String [] out = new String[al.size()];
        return al.toArray(out);
    } else {
        return null;
    }
}

搜索文本文件并在Java中返回数组

1 个答案: