如何等待线程完成以返回到先前的代码

Question

I have a question regarding threads. I have a method that reads an Excel spreadsheet and saves the data in a database. However, this method also checks the contents of a cell is an expected value, and if not, a frame must be called for the user to choose the most appropriate option. As it is written the code, it is not waiting for the frame open for the user to choose an option so he returns to the initial loop. (For the post would not be too long, I have omitted parts of the code, leaving only what matters) The following parts of the code:

public HashMap<String, Historico> importaDadosDoExcel(){
    HashMap<String, Historico> mapa = new HashMap<String, Historico>();
    HSSFCell cell= null;
    HSSFRow row = null;
    Historico update = new Historico();
    int rowsCount = 0;
    String[] statusStr = {"Aguardando Boleto", "Aguardando Lançamento", "Em Workflow","Liberado para Tesouraria", "Pago", "Outros"};
    String aux;
    for (int i = 1; i <= rowsCount; i++) {
        cell = row.getCell(ActvUtils.u.devolveNumColuna("D"));
        aux = ActvUtils.u.devolveCampoLido(cell);
        if (Arrays.asList(statusStr).contains(aux)) {
            update.setStatus(aux);
        }else{
            //Here, I would like the frame was called (passing as a parameter the value read in the cell) to which the user then chooses the best option, then, that choice was setted in the object.
            Runnable runnable = new EscolheStatus(aux); 
            Thread thread = new Thread(runnable);
            thread.start();
            //Here, I would like to read the option that the user chose on a string, some like:
            // String str = runnable.getStatus();
        }
    }
    return mapa;    
}

And now, my frame class:

public class EscolheStatus extends JFrame implements ActionListener,Runnable{


private String[] statusStr = {"Aguardando Boleto", "Aguardando Lançamento", "Em Workflow","Liberado para Tesouraria", "Pago", "Outros"};

private JRadioButton boleto;
private JRadioButton lancamento;
private JRadioButton workflow;
private JRadioButton tesouraria;
private JRadioButton pago;
private JRadioButton outros;

private String status;
private String statusEncontrado;

public EscolheStatus(String statusEncontrado){

    this.statusEncontrado = statusEncontrado;

    boleto = new JRadioButton(statusStr[0]);
    boleto.addActionListener(this);

    lancamento = new JRadioButton(statusStr[1]);
    lancamento.addActionListener(this);

    workflow = new JRadioButton(statusStr[2]);
    workflow.addActionListener(this);

    tesouraria = new JRadioButton(statusStr[3]);
    tesouraria.addActionListener(this);

    pago = new JRadioButton(statusStr[4]);
    pago.addActionListener(this);

    outros = new JRadioButton(statusStr[5]);
    outros.addActionListener(this);

    ButtonGroup group = new ButtonGroup();
    group.add(boleto);
    group.add(lancamento);
    group.add(workflow);
    group.add(tesouraria);
    group.add(pago);
    group.add(outros);

    JPanel radioPanel = new JPanel();
    radioPanel.setLayout(new GridLayout(6, 1));
    radioPanel.add(boleto);
    radioPanel.add(lancamento);
    radioPanel.add(workflow);
    radioPanel.add(tesouraria);
    radioPanel.add(pago);
    radioPanel.add(outros);

    radioPanel.setBorder(BorderFactory.createTitledBorder(BorderFactory.createEtchedBorder(), "Status '" + statusEncontrado + "' não reconhecido.  Escolha:"  ));
    setContentPane(radioPanel);  
    pack(); 
    this.setSize(350, 200);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setLocationRelativeTo(null);  
    this.setVisible(true);
    teste();

}

@Override
public void actionPerformed(ActionEvent ev) {
    Object opcao = ev.getSource();

    if(opcao.equals(boleto)){
        status = statusStr[0];
    }else if(opcao.equals(lancamento)){
        status = statusStr[1];
    }else if(opcao.equals(workflow)){
        status = statusStr[2];
    }else if(opcao.equals(tesouraria)){
        status = statusStr[3];
    }else if(opcao.equals(pago)){
        status = statusStr[4];
    }else if(opcao.equals(outros)){
        status = statusStr[5];
    }

    this.dispose();
}

public String getStatus() {
    return status;
}

public void setStatus(String status) {
    this.status = status;
}

@Override
public void run() {
    new EscolheStatus(statusEncontrado);

}

}

Answer 1

Here's an example of what MasterBlaster suggested (if it's only to stop the thread to require user input):

Thread worker = new Thread(new Runnable() {      
  @Override
  public void run() {
    long start = System.currentTimeMillis();

    while( (System.currentTimeMillis() - start) < 10000) {          
      System.out.println( "opening dialog" );
      String result = JOptionPane.showInputDialog( "Tell me something!" );
      System.out.println("user entered: " + result);
    }        

    System.out.println("finished");
  }
});

worker.run();

This will open a dialog and wait for the input again and again until the thread ran for at least 10 seconds.

You should be able to adapt that to your needs.

Of course, if multiple (worker) threads need to communicate you could use Thread.join() to wait for the other thread to finish or wait() and notify() if both threads need to run in parallel and one would just have to finish some task and then continue.

Edit : // String str = runnable.getStatus(); implies you want to get some information about a still running thread. In that case you could use a shared object to write to and read from (you might need some synchronization).