返回null什麼都不做

Question

我的程序已完成90％的任務，但我不斷收到一個錯誤。它說：「如果WavIO.read（）返回null，則不應當對當前樣本數組進行更改。」不知道要改變什麼。此外，進出口新的寫作的javadoc，什麼正確的方式來寫的構造函數/方法和一個javadoc的@params等。這裏是我的代碼：

public class Sound 
{ 
private String fileName; 
private double [] samples; 
/** 
* initializes the empty Sound array. 
*/ 
public Sound() { 
    this.samples = new double[0]; 
} 
/** 
* Makes copy sound object of given sound. 
*/ 
public Sound(Sound pSound) { 
    double[] temp; 
    temp = new double[pSound.samples.length]; 
    for (int i = 0; i < temp.length; i++) { 
     temp[i] = pSound.samples[i]; 
    } 
    this.samples = temp; 
} 
/** 
* get the array of sound samples 
* @return samples 
*/ 
public double[] get() { 
    return samples; 
} 
/** 
* increase volume of sound by given percent 
* @param double how much to increase volume by 
*/ 
public void increaseVol(double percent) { 
    // percent = percent/100.0; 
    for (int i = 0; i < samples.length; i++) { 
     samples[i] = samples[i] * (1.0 + percent); 
    } 
} 
/** 
* reduce volume of sound by given percent 
* @param double how much to reduce volume by 
*/ 
public void reduceVol(double percent) { 
    //percent = percent/100.0; 
    for (int i = 0; i < samples.length; i++) { 
     samples[i] = samples[i] * (1.0 - percent); 
    } 
} 
/** 
* lengthen sound duration by two 
*/ 
public void lengthen() { 
    double[]t = new double[samples.length]; 

    for (int i = 0; i < samples.length; i++) { 
     t[i] = samples[i]; 
    } 
    samples = new double[t.length * 2]; 
    for (int i = 0; i < samples.length; i++) { 
     samples[i] = t[i/2]; 
    } 
} 
/** 
* shorten sound duration by half. 
*/ 
public void shorten() { 
    double[]t = new double[samples.length]; 
    if (samples.length % 2 == 0) { 
     t = new double[samples.length/2]; 
    } 
    else { 
     t = new double[samples.length/2 + 1]; 
    } 
    int j = 0; 
    for (int i = 0; i < t.length; i++) { 
     t[i] = samples[j]; 
     j = j + 2; 
    } 
    samples = t; 
} 
/** 
* reverse the sound 
*/ 
public void reverse() { 
    for (int i = 0; i < samples.length/2; i++) { 
     double temp = samples[i]; 
     samples[i] = samples[samples.length - 1 - i]; 
     samples[samples.length - 1 - i] = temp; 
    } 
} 
/** 
* set array of sound samples 
*/ 
public void set(double[] mySamples) { 
    if (mySamples == null) { 
     throw new IllegalArgumentException("null"); 
    } 
    else { 
     samples = new double[mySamples.length]; 
     for (int i = 0; i < mySamples.length; i++) { 
      samples[i] = mySamples[i]; 
     } 
    } 
}  
/** 
* read a Wav file of given file name 
*/ 
public void wavRead(String fileName) { 
    this.samples = WavIO.read(fileName); 
} 
/** 
* save sound sample giving it a name 
*/ 
public void wavSave(String fileName) { 
    WavIO.write(fileName, samples); 
} 

}

Answer 1

public void wavRead(String fileName) { 
    double[] fileContents = WavIO.read(fileName); 
    if (fileContents != null) { 
     this.samples = fileContents; 
    } 
} 

回覆你的第二個問題，我建議你找一個關於Javadocs的教程。 「如何寫Javadoc」太寬泛，無法在這裏完全回答。