[英]How do I check if my editText field is empty and make it go to a new activity with a Button?
我已经做了这个代码：
public class MainActivity extends AppCompatActivity {
private ImageButton ourButton;
private EditText operand1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find Views by IDs :
ourButton = (ImageButton) findViewById(R.id.gobutton);
operand1 = (EditText) findViewById(R.id.edit_Name);
String ed_text = operand1.getText().toString().trim();
if(ed_text.isEmpty() || ed_text.length() == 0 || ed_text.equals("") || ed_text == null)
{
ourButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(MainActivity.this, "You did not enter a username", Toast.LENGTH_LONG).show();
}
});
}
else
{
ourButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent myIntent = new Intent(MainActivity.this, ScreenName.class);
MainActivity.this.startActivity(myIntent);
}
});
}
}
问题是，如果我在字段中输入或不输入任何内容的情况下按下按钮，它会说：
您没有输入用户名
下一个活动也不会起作用。
如何制作按钮以将用户移至下一个活动，同时确保他输入了姓名？
Use this, I have modified your code..
public class MainActivity extends AppCompatActivity {
private ImageButton ourButton;
private EditText operand1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find Views by IDs :
ourButton = (ImageButton) findViewById(R.id.gobutton);
operand1 = (EditText) findViewById(R.id.edit_Name);
ourButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String ed_text = operand1.getText().toString().trim();
if(ed_text.equals(""))
{
Toast.makeText(MainActivity.this, "You did not enter a username", Toast.LENGTH_LONG).show();
}
else
{
Intent myIntent = new Intent(MainActivity.this, ScreenName.class);
MainActivity.this.startActivity(myIntent);
}
}
});
}
问题是您没有检查侦听器中的值。 改成这样：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find Views by IDs :
ourButton = (ImageButton) findViewById(R.id.gobutton);
operand1 = (EditText) findViewById(R.id.edit_Name);
ourButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (operand1.getText().toString().trim().length() > 0) {
Intent myIntent = new Intent(MainActivity.this, ScreenName.class);
MainActivity.this.startActivity(myIntent);
} else {
Toast.makeText(MainActivity.this, "You did not enter a username", Toast.LENGTH_LONG).show();
}
}
});
}
在创建 Activity 时也会调用 onCreate，因此您无法在其中检查 name 字段的值。 这就是为什么您需要在按钮的单击侦听器中移动该检查。 然后，当您单击按钮时，它会始终检查名称字段是否为空。
您需要在按下按钮时进行检查，这是一个示例：
public class MainActivity extends AppCompatActivity {
private ImageButton ourButton;
private EditText operand1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find Views by IDs :
ourButton = (ImageButton) findViewById(R.id.gobutton);
operand1 = (EditText) findViewById(R.id.edit_Name);
ourButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(operand1.getText().length() == 0){
Toast.makeText(MainActivity.this, "You did not enter a username", Toast.LENGTH_LONG).show();
}else{
Intent myIntent = new Intent(MainActivity.this, ScreenName.class);
MainActivity.this.startActivity(myIntent);
}
}
});
}
}
试试这个...
public class MainActivity extends AppCompatActivity {
private ImageButton ourButton;
private EditText operand1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find Views by IDs :
ourButton = (ImageButton) findViewById(R.id.gobutton);
operand1 = (EditText) findViewById(R.id.edit_Name);
String ed_text = operand1.getText().toString().trim();
ourButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(ed_text.isEmpty() || ed_text.length() == 0 || ed_text.equals("") || ed_text == null) {
Toast.makeText(MainActivity.this, "You did not enter a username", Toast.LENGTH_LONG).show();
} else {
Intent myIntent = new Intent(MainActivity.this, ScreenName.class);
MainActivity.this.startActivity(myIntent);
}
});
}
}
你可以试试这个代码：
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private ImageButton ourButton;
private EditText operand1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find Views by IDs :
ourButton = (ImageButton) findViewById(R.id.gobutton);
operand1 = (EditText) findViewById(R.id.edit_Name);
ourButton.setOnClickListener(this);
}
@Override
public void onClick(View v) {
int id = v.getId();
if (id == R.id.gobutton) {
if(operand1.getText().toString().trim().equals("")){
Toast.makeText(MainActivity.this, "You did not enter a username", Toast.LENGTH_LONG).show()
}else{
Intent myIntent = new Intent(this,ScreenName.class);
startActivity(myIntent);
}
}
}
像这样改变你的代码
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private ImageButton ourButton;
private EditText operand1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find Views by IDs :
ourButton = (ImageButton) findViewById(R.id.gobutton);
operand1 = (EditText) findViewById(R.id.edit_Name);
ourButton.setOnClickListener(this);
}
@Override
public void onClick(View view) {
String ed_text = operand1.getText().toString().trim();
if(ed_text.equals("")){
Toast.makeText(MainActivity.this, "You did not enter a username", Toast.LENGTH_LONG).show()
}else{
Intent myIntent = new Intent(MainActivity.this, ScreenName.class);
MainActivity.this.startActivity(myIntent);
}
}
}
你可以用这个
public class MainActivity extends AppCompatActivity {
private ImageButton ourButton;
private EditText operand1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Find Views by IDs :
ourButton = (ImageButton) findViewById(R.id.gobutton);
operand1 = (EditText) findViewById(R.id.edit_Name);
String ed_text = operand1.getText().toString();
ourButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(ed_text.equalsignorcase("")
{
Toast.makeText(MainActivity.this, "You did not enter a username", Toast.LENGTH_LONG).show();
}
else
{
Intent myIntent = new Intent(MainActivity.this, ScreenName.class);
MainActivity.this.startActivity(myIntent);
}
});
}
不要为一个按钮设置两个 OnClickListeners
尝试以下代码 -
String ed_text = operand1.getText().toString().trim();
ourButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(!TextUtils.isEmpty(ed_text)){
Toast.makeText(MainActivity.this, "Not Empty", Toast.LENGTH_SHORT).show();
Intent myIntent = new Intent(MainActivity.this, ScreenName.class);
startActivity(myIntent);
finish(); //If you want to kill current Activity.
}else{
Toast.makeText(MainActivity.this, "Empty", Toast.LENGTH_SHORT).show();
}
}
});
希望它会有所帮助:)
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