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Chapter 25 The java.lang Package |
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Chapter 25 The java.lang Package |
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The String class represents a string of characters. A String object is created by the Java compiler whenever it encounters a string in doublequotes--this method of creation is usually simpler than using a constructor. A number of the methods of this class provide useful string manipulation functions. length() returns the number of characters in a string. charAt() extracts a character from a string. compareTo() compares two strings. equalsIgnoreCase() tests string for equality, ignoring case. startsWith() and endsWith() compare the start and end of a string to a specified value. indexOf() and lastIndexOf() search forward and backwards in a string for a specified character or substring. substring() returns a substring of a string. replace() creates a new copy of the string with one character replaced by another. toUpperCase() and toLowerCase() convert the case of a string. trim() strips whitespace from the start and end of a string. concat() concatenates two strings, which can also be done with the + operator.
Note that String objects are immutable--there is no setCharAt() method to change the contents. The methods above that return a String do not modify the string they are passed, but instead return a modified copy of the string. Use a StringBuffer if you want to manipulate the contents of a string, or use toCharArray() to convert a string to an array of char values.
The static valueOf() methods convert various Java primitive types to strings.
public final class String extends Object implements Serializable {
// Public Constructors
public String();
public String(String value);
public String(char[] value);
public String(char[] value, int offset, int count);
# public String(byte[] ascii, int hibyte, int offset, int count);
# public String(byte[] ascii, int hibyte);
1.1public String(byte[] bytes, int offset, int length, String enc) throws UnsupportedEncodingException;
1.1public String(byte[] bytes, String enc) throws UnsupportedEncodingException;
1.1public String(byte[] bytes, int offset, int length);
1.1public String(byte[] bytes);
public String(StringBuffer buffer);
// Class Methods
public static String copyValueOf(char[] data, int offset, int count);
public static String copyValueOf(char[] data);
public static String valueOf(Object obj);
public static String valueOf(char[] data);
public static String valueOf(char[] data, int offset, int count);
public static String valueOf(boolean b);
public static String valueOf(char c);
public static String valueOf(int i);
public static String valueOf(long l);
public static String valueOf(float f);
public static String valueOf(double d);
// Public Instance Methods
public char charAt(int index);
public int compareTo(String anotherString);
public String concat(String str);
public boolean endsWith(String suffix);
public boolean equals(Object anObject); // Overrides Object
public boolean equalsIgnoreCase(String anotherString);
# public void getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin);
1.1public byte[] getBytes(String enc) throws UnsupportedEncodingException;
1.1public byte[] getBytes();
public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin);
public int hashCode(); // Overrides Object
public int indexOf(int ch);
public int indexOf(int ch, int fromIndex);
public int indexOf(String str);
public int indexOf(String str, int fromIndex);
public native String intern();
public int lastIndexOf(int ch);
public int lastIndexOf(int ch, int fromIndex);
public int lastIndexOf(String str);
public int lastIndexOf(String str, int fromIndex);
public int length();
public boolean regionMatches(int toffset, String other, int ooffset, int len);
public boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len);
public String replace(char oldChar, char newChar);
public boolean startsWith(String prefix, int toffset);
public boolean startsWith(String prefix);
public String substring(int beginIndex);
public String substring(int beginIndex, int endIndex);
public char[] toCharArray();
1.1public String toLowerCase(Locale locale);
public String toLowerCase();
public String toString(); // Overrides Object
1.1public String toUpperCase(Locale locale);
public String toUpperCase();
public String trim();
}
Many methods
Many methods
BorderLayout.CENTER, BorderLayout.EAST, BorderLayout.NORTH, BorderLayout.SOUTH, BorderLayout.WEST, File.pathSeparator, File.separator, Font.name, HttpURLConnection.method, HttpURLConnection.responseMessage, InvalidClassException.classname, StreamTokenizer.sval, StringBufferInputStream.buffer
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| java.lang.StackOverflowError (JDK 1.0) |  |
java.lang.StringBuffer (JDK 1.0) |
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