Question

我的xml

<TextView 
        android:id="@+id/newPlaceLatLable"
        android:text="Place Latitude"
        android:layout_width="150dp"
        android:layout_height="40dp"
       android:layout_below="@id/newPlaceLable"/>
    <EditText
        android:id="@+id/newPlaceLat"
        android:layout_width="150dp"
        android:layout_height="40dp"
        android:layout_toRightOf="@id/newPlaceLatLable" 
         android:layout_below="@id/newPlaceLable"
         android:inputType="numberDecimal"
        />
    <TextView 
        android:id="@+id/newPlaceLonLable"
        android:text="Place Longitude"
        android:layout_width="150dp"
        android:layout_height="40dp"
       android:layout_below="@id/newPlaceLatLable"/>
    <EditText
        android:id="@+id/newPlaceLon"
        android:layout_width="150dp"
        android:layout_height="40dp"
        android:layout_toRightOf="@id/newPlaceLonLable" 
        android:layout_below="@id/newPlaceLatLable"
        android:inputType="numberDecimal"
        />

并在代码中

if (et1.getText().toString().matches(""))
            Toast.makeText(getApplicationContext(), "Name can't be null", Toast.LENGTH_SHORT).show();
        else if (et2.getText().toString().matches(""))
            Toast.makeText(getApplicationContext(), "Latitute can't be null", Toast.LENGTH_SHORT).show();
        else  if (et3.getText().toString().matches(""))
            Toast.makeText(getApplicationContext(), "Longitute can't be null", Toast.LENGTH_SHORT).show();

其中et1，et2和et3是

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_change);
        et1 = (EditText) findViewById(R.id.newPlaceText);        
         et2 = (EditText) findViewById(R.id.newPlaceLat);
         et3 = (EditText) findViewById(R.id.newPlaceLon);

但是每次我运行应用程序时，都会给予吐司“Latitute不能为空”。虽然et2中有文字，但它没有在这里显示。请好好看看。有什么问题

Answer 1

您可以选择 @blackbelt 建议或者像这样..

if (et1.getText().toString().equals(""))
            Toast.makeText(getApplicationContext(), "Name can't be null", Toast.LENGTH_SHORT).show();
else if (et2.getText().toString().equals(""))
            Toast.makeText(getApplicationContext(), "Latitute can't be null", Toast.LENGTH_SHORT).show();
else  if (et3.getText().toString().equals(""))
            Toast.makeText(getApplicationContext(), "Longitute can't be null", Toast.LENGTH_SHORT).show();

希望这会有所帮助...

Answer 2

您要检查EditText是否填充了相同的值。

matches("")

不是你需要的。

检查字符串的lenght是否为＆gt; 0，或使用equals("")

if (et1.getText().toString().length() <= 0)
            Toast.makeText(getApplicationContext(), "Name can't be null", Toast.LENGTH_SHORT).show();
else if (et2.getText().toString().length() <= 0)
            Toast.makeText(getApplicationContext(), "Latitute can't be null", Toast.LENGTH_SHORT).show();
else  if (et3.getText().toString().length() <= 0)
            Toast.makeText(getApplicationContext(), "Longitute can't be null", Toast.LENGTH_SHORT).show();

Answer 3

使用这种方式

if (et1.getText().toString().trim().length() <= 0)
            Toast.makeText(getApplicationContext(), "Name can't be null", Toast.LENGTH_SHORT).show();
else if (et2.getText().toString().trim().length() <= 0)
            Toast.makeText(getApplicationContext(), "Latitute can't be null", Toast.LENGTH_SHORT).show();
else  if (et3.getText().toString().trim().length() <= 0)
            Toast.makeText(getApplicationContext(), "Longitute can't be null", Toast.LENGTH_SHORT).show();

Answer 4

match（）＆amp;之间的区别equal（）是matches（）检查String与正则表达式模式的匹配，而equal（）将此Comparator与指定的Object进行比较并指示它们是否相等，请参阅此答案

https://stackoverflow.com/a/9700152/2240535

EditText始终显示为null

4 个答案: