java - 等待监听器完成任务并获取另一个函数的结果 [Android]

Question

我想从我的文件浏览器函数获取文件路径，但是我的文件浏览器函数有监听器，所以如果我在此文件浏览器函数之后调用另一个函数，它会崩溃，因为路径仍然是空的，这是我想调用的两个函数:

public void openFileExplorer() {
    File mPath = new File(Environment.getExternalStorageDirectory() + "/");
    fileDialog = new FileDialog(this, mPath);
    fileDialog.addFileListener(new FileDialog.FileSelectedListener() {
        public void fileSelected(File file) {
            Log.d(getClass().getName(), "selected file " + file.toString());
            chosenFile = file.toString();
        }
    });
    fileDialog.showDialog();
}

private void generateMFCC(String path) {
   // btnBrowse.setText("Done");
    Log.d(getClass().getName(), ": Success");
    buffer = mRecorder.ReadWave(path);
    data = new float[buffer.length];

    for (int i = 0; i < buffer.length; i++) {
        data[i] = (float) buffer[i];
    }
    //Toast.makeText(getApplicationContext(), "Success", Toast.LENGTH_SHORT).show();
    preProcess = new PreProcess(data, samplePerFreame, sampleRate);
    featureExtract = new FeatureExtract(preProcess.framedSignal, sampleRate, samplePerFreame);
    featureExtract.makeMfccFeatureVector();
    featureVector = featureExtract.getFeatureVector();
    double[][] fv = featureVector.getMfccFeature();

    for (int i = 0; i < fv.length; i++) {
        test = test + "{" + "\n";
        for (int j = 0; j < fv[i].length; j++) {
            test = test + Double.toString(fv[i][j]) + ", ";
        }
        test = test + "}" + "\n";
    }}

我这样调用该函数:

openFileExplorer();
generateMFCC(chosenFile);

但在文件资源管理器对话框打开之前总是出现错误

Answer 1

仅从 openFileExplorer 调用generateMFCC。

public void openFileExplorer() {
    File mPath = new File(Environment.getExternalStorageDirectory() + "/");
    fileDialog = new FileDialog(this, mPath);
    fileDialog.addFileListener(new FileDialog.FileSelectedListener() {
        public void fileSelected(File file) {
            Log.d(getClass().getName(), "selected file " + file.toString());
            chosenFile = file.toString();
generateMFCC(chosenFile);

        }
    });
    fileDialog.showDialog();
}