Question

您好我有一串数字，并希望将它们放入浮点数组中，以便我可以访问这些值。

// 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;
}

错误是

java nullpointerexception：尝试调用虚方法 java对象上的java.lang.string java.lang.split（java.lang.string）参考

感谢

除此之外，我想我需要解释一下，所以我提供了更多的代码来展示我想要做的事情。

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

您的代码的问题是初始化，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为空;修复它并尝试这个

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

Answer 3

您的数组初始化错误，应该像

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

经过长度你应该有一个分号而不是'，'

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

修改试试这个它会起作用

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

使用此 将字符串数组转换为字符串，然后转换float

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

然后添加浮点数组

将字符串传递给float数组？

4 个答案: