突出显示超出EditText限制的文本

Question

如何以红色突出显示超出EditText限制的文本，如下所示：

例如，我想要一个100个字符的限制。我该怎么做？ 这是来自YouTube应用。

Answer 1

您可以使用spannable绘制EditText文本的不同部分：

     final SpannableStringBuilder sb = new SpannableStringBuilder(charSequence.toString());
     final ForegroundColorSpan fcs = new ForegroundColorSpan(Color.rgb(158, 0, 0));
     //final StyleSpan bss = new StyleSpan(android.graphics.Typeface.BOLD); // You can make the text bold!
     sb.setSpan(fcs, yourTextLimit, charSequence.toString().length() - 1, Spannable.SPAN_INCLUSIVE_INCLUSIVE);

参考：This answer

将onChanged侦听器设置为EditText，当文本大小超出限制时，可以使用上面的代码更改文本颜色

例如

public class MainActivity extends AppCompatActivity {

    EditText test;

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


        test = (EditText) findViewById(R.id.test);

        test.addTextChangedListener(new TextWatcher() {
            boolean changed = true;

            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                int yourTextLimit = 10;
                final SpannableStringBuilder sb = new SpannableStringBuilder(charSequence.toString());

                if (charSequence.toString().length() > yourTextLimit && changed) {
                    final ForegroundColorSpan fcs = new ForegroundColorSpan(Color.rgb(158, 0, 0));
                    //final StyleSpan bss = new StyleSpan(android.graphics.Typeface.BOLD); // You can make the text bold!
                    // sb.setSpan(bss, yourTextLimit, charSequence.toString().length() - 1, Spannable.SPAN_INCLUSIVE_INCLUSIVE);
                    sb.setSpan(fcs, yourTextLimit, charSequence.toString().length(), Spannable.SPAN_INCLUSIVE_INCLUSIVE);
                    sb.setSpan(new MyClickableSpan(charSequence.toString()), 0, charSequence.toString().length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

                    changed = false;
                    test.setText(sb);
                } else if (changed) {
                    final ForegroundColorSpan fcs = new ForegroundColorSpan(Color.rgb(0, 0, 0));
                    sb.setSpan(fcs, 0, charSequence.toString().length(), Spannable.SPAN_INCLUSIVE_INCLUSIVE);
                    sb.setSpan(new MyClickableSpan(charSequence.toString()), 0, charSequence.toString().length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

                    changed = false;
                    test.setText(sb);
                }

                test.setSelection(charSequence.toString().length());
            }

            @Override
            public void afterTextChanged(Editable editable) {
                changed = true;
            }
        });

    }

    class MyClickableSpan extends ClickableSpan {// extend ClickableSpan

        String clicked;
        public MyClickableSpan(String string) {
            super();
            clicked = string;
        }

        public void onClick(View tv) {
            Toast.makeText(MainActivity.this,clicked , Toast.LENGTH_SHORT).show();
        }

        public void updateDrawState(TextPaint ds) {// override updateDrawState
            ds.setUnderlineText(false); // set to false to remove underline
        }
    }
}