將字符串傳遞給浮點數組？

Question

嗨，我有一串數字，想將它們放入浮點數組中，以便我可以訪問這些值。

// this bit works fine, data is split into string array.
String fdata[] = data.split(",");
Float array_f[] = new Float(fdata.length);

// this is the bit which throws an error and causes my app to crash.
for (int i = 0; i < fdata.length; i++){
    float y = Float.parseFloat(fdata[i]);
    array_f[i] = y;
}

錯誤是一個

java nullpointerexception：嘗試在空對象引用上調用虛擬方法 java.lang.string java.lang.split(java.lang.string)。

謝謝

除此之外，我想我需要多解釋一下，所以我提供了更多的代碼來展示我想要做什么。

String data; //does this need to define the number of bytes needed then?

start_Acq.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
    channel_a = String.valueOf(channel_Acq.getSelectedItem());
    Thread thread = new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                connection.start_acquisition(channel_a);
                data = connection.start_acquisition(channel_a);
                connection.stop_acquisition();
            }catch (Exception e ){
                e.printStackTrace();
            }
        }
    });thread.start();

    data_recived.setText(data);
    String fdata[] = data.split(",");
    Float array_f[] = new Float[fdata.length];

    for(int i = 0; i<fdata.length; i++){
        float y = Float.parseFloat(fdata[i]);
        array_f[i] = y;
    }

}
});

Answer 1

您的代碼的問題在於初始化，您所要做的就是使用原始 float 而不是 Float ：

 String data = "123,5468,1,25,36";
    String fdata[] = data.split(",");
    float array_f[] = new float[fdata.length];
    for (int i = 0; i < fdata.length; i++){
        array_f[i] = Float.parseFloat(fdata[i]);
System.out.println(array_f[i]);
}

Answer 2

首先data為空； 修復它並嘗試這個

float y = java.lang.Float.parseFloat(fdata[i]);

Answer 3

你的數組初始化錯誤，應該是這樣

Float array_f[] = new Float[fdata.length];

在長度之后你應該有一個分號而不是','

for (int i=0; i<fdata.length;i++){

編輯試試這個它會工作

String fdata[] = new String[]{"6.5", "8.5"};           //this bit works fine, data is split into string array.
        Float array_f[] = new Float[fdata.length];
        for (int i = 0; i < fdata.length; i++) {          //this is the bit which throws an error and causes my app to crash.
            float y = Float.parseFloat(fdata[i]);
            array_f[i] = y;
        }
        System.out.println(Arrays.asList(array_f));

Answer 4

使用這個獲取字符串數組到字符串然后轉換浮點數

 for(int i=0;stringarray.length>i;i++){float_var = Float.valueOf(string_array.get(i)); float_array.add(float_var);}

然后添加浮點數組