[英]How do I check if my editText field is empty and make it go to a new activity with a Button?
我已經做了這個代碼：
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);
}
});
}
}
問題是，如果我在字段中輸入或不輸入任何內容的情況下按下按鈕，它會說：
您沒有輸入用戶名
下一個活動也不會起作用。
如何制作按鈕以將用戶移至下一個活動，同時確保他輸入了姓名？
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);
}
}
});
}
問題是您沒有檢查偵聽器中的值。 改成這樣：
@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();
}
}
});
}
在創建 Activity 時也會調用 onCreate，因此您無法在其中檢查 name 字段的值。 這就是為什么您需要在按鈕的單擊偵聽器中移動該檢查。 然后，當您單擊按鈕時，它會始終檢查名稱字段是否為空。
您需要在按下按鈕時進行檢查，這是一個示例：
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);
}
}
});
}
}
試試這個...
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);
}
});
}
}
你可以試試這個代碼：
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);
}
}
}
像這樣改變你的代碼
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);
}
}
}
你可以用這個
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);
}
});
}
不要為一個按鈕設置兩個 OnClickListeners
嘗試以下代碼 -
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();
}
}
});
希望它會有所幫助:)
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