Layout样式：
layout 代码：
MainActivity的逻辑实现：
package com.example.counttestapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private EditText edt_intro;
private TextView count;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
edt_intro = findViewById(R.id.edt_intro);
count = findViewById(R.id.count);
initEvent();
}
private void initEvent() {
edt_intro.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void afterTextChanged(Editable s) {
count.setText(String.valueOf(s.length()+"/500"));
if(s.length()>=500){
Toast.makeText(MainActivity.this, "字数超过", Toast.LENGTH_SHORT).show();
}
}
});
}
}
