你如何在textview上打印android工作室代码中的字符串字符

Question

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;



public class MainActivity extends AppCompatActivity {

    private TextView textView;
    private EditText editText;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView = findViewById(R.id.textView);
        editText = findViewById(R.id.editText);


    }
    public void display(View view)
    {
        String str=editText.getText().toString();
        char first=str.charAt(0);

        textView.setText(first);














  }

}

/*this code is to take input into a editText and then print characters of that string on the textView but i am not able to achieve that even thought the code doesn't show any errors on android studio code */

// whenever i press the button which is connected to the display function it just crashes the app*/

Answer 1

setText() takes a CharSequence as parameter, not a char . Use substring instead of chartAt .

String str = editText.getText().toString();
String first = str.substring(0,1);
textView.setText(first);