String utility for Android

StringUtils.java

package com.r384ta.android.betterstructure.util;

import android.support.annotation.IntDef;
import android.support.annotation.Nullable;

public class StringUtils {
  public static final int DEFAULT = 0;
  public static final int ASCII_TRIM = 1;
  public static final int FULL_TRIM = 2;

  public static boolean isEmpty(@Nullable CharSequence text) {
    return text == null || text.length() == 0 || isEmpty(text, DEFAULT);
  }

  public static boolean isEmpty(@Nullable CharSequence text, @EmptyType int type) {
    if (text == null || text.length() == 0) return true;

    if (type == DEFAULT) {
      return text.toString().isEmpty();
    } else if (type == ASCII_TRIM) {
      return text.toString().trim().isEmpty();
    } else {
      return trim(text.toString()).isEmpty();
    }
  }

  public static String trim(@Nullable String text) {
    if (text == null) return null;

    char[] val = text.toCharArray();
    int len = val.length;
    int st = 0;

    while ((st < len) && (val[len - 1] <= ' ' || val[len - 1] == '　')) {
      len--;
    }

    return ((len < val.length)) ? text.substring(st, len) : text;
  }

  @IntDef(value = {DEFAULT, ASCII_TRIM, FULL_TRIM})
  public @interface EmptyType {
  }
}

StringUtilsTest.java

package com.r384ta.android.betterstructure;

import com.r384ta.android.betterstructure.util.StringUtils;

import org.junit.Test;

import static com.r384ta.android.betterstructure.util.StringUtils.ASCII_TRIM;
import static com.r384ta.android.betterstructure.util.StringUtils.FULL_TRIM;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;

public class StringUtilsTest {
  @Test
  public void testIsEmpty() throws Exception {
    // Basic
    assertTrue(StringUtils.isEmpty(null));
    assertTrue(StringUtils.isEmpty(""));
    assertFalse(StringUtils.isEmpty("こんにちは"));
    assertFalse(StringUtils.isEmpty("   "));
    assertFalse(StringUtils.isEmpty("　　"));

    // Ascii trim
    assertTrue(StringUtils.isEmpty(null, ASCII_TRIM));
    assertTrue(StringUtils.isEmpty("", ASCII_TRIM));
    assertFalse(StringUtils.isEmpty("こんにちは", ASCII_TRIM));
    assertTrue(StringUtils.isEmpty("   ", ASCII_TRIM));
    assertFalse(StringUtils.isEmpty("　　", ASCII_TRIM));

    // Full trim
    assertTrue(StringUtils.isEmpty(null, FULL_TRIM));
    assertTrue(StringUtils.isEmpty("", FULL_TRIM));
    assertFalse(StringUtils.isEmpty("こんにちは", FULL_TRIM));
    assertTrue(StringUtils.isEmpty("   ", FULL_TRIM));
    assertTrue(StringUtils.isEmpty("　　", FULL_TRIM));
  }

  @Test
  public void testTrim() throws Exception {
    assertNull(StringUtils.trim(null));
    assertEquals(StringUtils.trim(""), "");
    assertEquals(StringUtils.trim("こんにちは"), "こんにちは");
    assertEquals(StringUtils.trim("   "), "");
    assertEquals(StringUtils.trim("　　"), "");
  }
}